diff --git a/MultiServer.py b/MultiServer.py
index ed14b6506f..126672a760 100644
--- a/MultiServer.py
+++ b/MultiServer.py
@@ -44,8 +44,9 @@ import NetUtils
 import Utils
 from Utils import version_tuple, restricted_loads, Version, async_start, get_intended_text
 from NetUtils import Endpoint, ClientStatus, NetworkItem, decode, encode, NetworkPlayer, Permission, NetworkSlot, \
-    SlotType, LocationStore, MultiData, Hint, HintStatus
+    SlotType, LocationStore, MultiData, Hint, HintStatus, GamesPackage
 from BaseClasses import ItemClassification
+from apmw.multiserver.gamespackagecache import GamesPackageCache
 
 
 min_client_version = Version(0, 5, 0)
@@ -241,21 +242,38 @@ class Context:
     slot_info: typing.Dict[int, NetworkSlot]
     generator_version = Version(0, 0, 0)
     checksums: typing.Dict[str, str]
+    played_games: set[str]
     item_names: typing.Dict[str, typing.Dict[int, str]]
-    item_name_groups: typing.Dict[str, typing.Dict[str, typing.Set[str]]]
+    item_name_groups: typing.Dict[str, typing.Dict[str, list[str]]]
     location_names: typing.Dict[str, typing.Dict[int, str]]
-    location_name_groups: typing.Dict[str, typing.Dict[str, typing.Set[str]]]
+    location_name_groups: typing.Dict[str, typing.Dict[str, list[str]]]
     all_item_and_group_names: typing.Dict[str, typing.Set[str]]
     all_location_and_group_names: typing.Dict[str, typing.Set[str]]
     non_hintable_names: typing.Dict[str, typing.AbstractSet[str]]
     spheres: typing.List[typing.Dict[int, typing.Set[int]]]
     """ each sphere is { player: { location_id, ... } } """
+    games_package_cache: GamesPackageCache
     logger: logging.Logger
 
-    def __init__(self, host: str, port: int, server_password: str, password: str, location_check_points: int,
-                 hint_cost: int, item_cheat: bool, release_mode: str = "disabled", collect_mode="disabled",
-                 countdown_mode: str = "auto", remaining_mode: str = "disabled", auto_shutdown: typing.SupportsFloat = 0, 
-                 compatibility: int = 2, log_network: bool = False, logger: logging.Logger = logging.getLogger()):
+    def __init__(
+            self,
+            host: str,
+            port: int,
+            server_password: str,
+            password: str,
+            location_check_points: int,
+            hint_cost: int,
+            item_cheat: bool,
+            release_mode: str = "disabled",
+            collect_mode="disabled",
+            countdown_mode: str = "auto",
+            remaining_mode: str = "disabled",
+            auto_shutdown: typing.SupportsFloat = 0,
+            compatibility: int = 2,
+            log_network: bool = False,
+            games_package_cache: GamesPackageCache | None = None,
+            logger: logging.Logger = logging.getLogger(),
+    ) -> None:
         self.logger = logger
         super(Context, self).__init__()
         self.slot_info = {}
@@ -306,6 +324,7 @@ class Context:
         self.save_dirty = False
         self.tags = ['AP']
         self.games: typing.Dict[int, str] = {}
+        self.played_games = set()
         self.minimum_client_versions: typing.Dict[int, Version] = {}
         self.seed_name = ""
         self.groups = {}
@@ -315,9 +334,10 @@ class Context:
         self.stored_data_notification_clients = collections.defaultdict(weakref.WeakSet)
         self.read_data = {}
         self.spheres = []
+        self.games_package_cache = games_package_cache or GamesPackageCache()
 
         # init empty to satisfy linter, I suppose
-        self.gamespackage = {}
+        self.reduced_games_package = {}
         self.checksums = {}
         self.item_name_groups = {}
         self.location_name_groups = {}
@@ -329,50 +349,11 @@ class Context:
             lambda: Utils.KeyedDefaultDict(lambda code: f'Unknown location (ID:{code})'))
         self.non_hintable_names = collections.defaultdict(frozenset)
 
-        self._load_game_data()
-
-    # Data package retrieval
-    def _load_game_data(self):
-        import worlds
-        self.gamespackage = worlds.network_data_package["games"]
-
-        self.item_name_groups = {world_name: world.item_name_groups for world_name, world in
-                                 worlds.AutoWorldRegister.world_types.items()}
-        self.location_name_groups = {world_name: world.location_name_groups for world_name, world in
-                                     worlds.AutoWorldRegister.world_types.items()}
-        for world_name, world in worlds.AutoWorldRegister.world_types.items():
-            self.non_hintable_names[world_name] = world.hint_blacklist
-
-        for game_package in self.gamespackage.values():
-            # remove groups from data sent to clients
-            del game_package["item_name_groups"]
-            del game_package["location_name_groups"]
-
-    def _init_game_data(self):
-        for game_name, game_package in self.gamespackage.items():
-            if "checksum" in game_package:
-                self.checksums[game_name] = game_package["checksum"]
-            for item_name, item_id in game_package["item_name_to_id"].items():
-                self.item_names[game_name][item_id] = item_name
-            for location_name, location_id in game_package["location_name_to_id"].items():
-                self.location_names[game_name][location_id] = location_name
-            self.all_item_and_group_names[game_name] = \
-                set(game_package["item_name_to_id"]) | set(self.item_name_groups[game_name])
-            self.all_location_and_group_names[game_name] = \
-                set(game_package["location_name_to_id"]) | set(self.location_name_groups.get(game_name, []))
-
-        archipelago_item_names = self.item_names["Archipelago"]
-        archipelago_location_names = self.location_names["Archipelago"]
-        for game in [game_name for game_name in self.gamespackage if game_name != "Archipelago"]:
-            # Add Archipelago items and locations to each data package.
-            self.item_names[game].update(archipelago_item_names)
-            self.location_names[game].update(archipelago_location_names)
-
     def item_names_for_game(self, game: str) -> typing.Optional[typing.Dict[str, int]]:
-        return self.gamespackage[game]["item_name_to_id"] if game in self.gamespackage else None
+        return self.reduced_games_package[game]["item_name_to_id"] if game in self.reduced_games_package else None
 
     def location_names_for_game(self, game: str) -> typing.Optional[typing.Dict[str, int]]:
-        return self.gamespackage[game]["location_name_to_id"] if game in self.gamespackage else None
+        return self.reduced_games_package[game]["location_name_to_id"] if game in self.reduced_games_package else None
 
     # General networking
     async def send_msgs(self, endpoint: Endpoint, msgs: typing.Iterable[dict]) -> bool:
@@ -482,19 +463,17 @@ class Context:
             with open(multidatapath, 'rb') as f:
                 data = f.read()
 
-        self._load(self.decompress(data), {}, use_embedded_server_options)
+        self._load(self.decompress(data), use_embedded_server_options)
         self.data_filename = multidatapath
 
     @staticmethod
-    def decompress(data: bytes) -> dict:
+    def decompress(data: bytes) -> typing.Any:
         format_version = data[0]
         if format_version > 3:
             raise Utils.VersionException("Incompatible multidata.")
         return restricted_loads(zlib.decompress(data[1:]))
 
-    def _load(self, decoded_obj: MultiData, game_data_packages: typing.Dict[str, typing.Any],
-              use_embedded_server_options: bool):
-
+    def _load(self, decoded_obj: MultiData, use_embedded_server_options: bool) -> None:
         self.read_data = {}
         # there might be a better place to put this.
         race_mode = decoded_obj.get("race_mode", 0)
@@ -515,6 +494,7 @@ class Context:
 
         self.slot_info = decoded_obj["slot_info"]
         self.games = {slot: slot_info.game for slot, slot_info in self.slot_info.items()}
+        self.played_games = {"Archipelago"} | {self.games[x] for x in range(1, len(self.games) + 1)}
         self.groups = {slot: set(slot_info.group_members) for slot, slot_info in self.slot_info.items()
                        if slot_info.type == SlotType.group}
 
@@ -559,18 +539,11 @@ class Context:
             server_options = decoded_obj.get("server_options", {})
             self._set_options(server_options)
 
-        # embedded data package
-        for game_name, data in decoded_obj.get("datapackage", {}).items():
-            if game_name in game_data_packages:
-                data = game_data_packages[game_name]
-            self.logger.info(f"Loading embedded data package for game {game_name}")
-            self.gamespackage[game_name] = data
-            self.item_name_groups[game_name] = data["item_name_groups"]
-            if "location_name_groups" in data:
-                self.location_name_groups[game_name] = data["location_name_groups"]
-                del data["location_name_groups"]
-            del data["item_name_groups"]  # remove from data package, but keep in self.item_name_groups
+        # load and apply world data and (embedded) data package
+        self._load_world_data()
+        self._load_data_package(decoded_obj.get("datapackage", {}))
         self._init_game_data()
+
         for game_name, data in self.item_name_groups.items():
             self.read_data[f"item_name_groups_{game_name}"] = lambda lgame=game_name: self.item_name_groups[lgame]
         for game_name, data in self.location_name_groups.items():
@@ -579,6 +552,55 @@ class Context:
         # sorted access spheres
         self.spheres = decoded_obj.get("spheres", [])
 
+    def _load_world_data(self) -> None:
+        import worlds
+
+        for world_name, world in worlds.AutoWorldRegister.world_types.items():
+            # TODO: move hint_blacklist into GamesPackage?
+            self.non_hintable_names[world_name] = world.hint_blacklist
+
+    def _load_data_package(self, data_package: dict[str, GamesPackage]) -> None:
+        """Populates reduced_games_package, item_name_groups, location_name_groups from static data and data_package"""
+        # NOTE: for worlds loaded from db, only checksum is set in GamesPackage, but this is handled by cache
+        for game_name in sorted(self.played_games):
+            if game_name in data_package:
+                self.logger.info(f"Loading embedded data package for game {game_name}")
+                data = self.games_package_cache.get(game_name, data_package[game_name])
+            else:
+                # NOTE: we still allow uploading a game without datapackage. Once that is changed, we could drop this.
+                data = self.games_package_cache.get_static(game_name)
+            (
+                self.reduced_games_package[game_name],
+                self.item_name_groups[game_name],
+                self.location_name_groups[game_name],
+            ) = data
+
+        del self.games_package_cache  # Not used past this point. Free memory.
+
+    def _init_game_data(self) -> None:
+        """Update internal values from previously loaded data packages"""
+        for game_name, game_package in self.reduced_games_package.items():
+            if game_name not in self.played_games:
+                continue
+            if "checksum" in game_package:
+                self.checksums[game_name] = game_package["checksum"]
+            # NOTE: we could save more memory by moving the stuff below to data package cache as well
+            for item_name, item_id in game_package["item_name_to_id"].items():
+                self.item_names[game_name][item_id] = item_name
+            for location_name, location_id in game_package["location_name_to_id"].items():
+                self.location_names[game_name][location_id] = location_name
+            self.all_item_and_group_names[game_name] = \
+                set(game_package["item_name_to_id"]) | set(self.item_name_groups[game_name])
+            self.all_location_and_group_names[game_name] = \
+                set(game_package["location_name_to_id"]) | set(self.location_name_groups.get(game_name, []))
+
+        archipelago_item_names = self.item_names["Archipelago"]
+        archipelago_location_names = self.location_names["Archipelago"]
+        for game in [game_name for game_name in self.reduced_games_package if game_name != "Archipelago"]:
+            # Add Archipelago items and locations to each data package.
+            self.item_names[game].update(archipelago_item_names)
+            self.location_names[game].update(archipelago_location_names)
+
     # saving
 
     def save(self, now=False) -> bool:
@@ -919,12 +941,10 @@ async def server(websocket: "ServerConnection", path: str = "/", ctx: Context =
 
 
 async def on_client_connected(ctx: Context, client: Client):
-    games = {ctx.games[x] for x in range(1, len(ctx.games) + 1)}
-    games.add("Archipelago")
     await ctx.send_msgs(client, [{
         'cmd': 'RoomInfo',
         'password': bool(ctx.password),
-        'games': games,
+        'games': sorted(ctx.played_games),
         # tags are for additional features in the communication.
         # Name them by feature or fork, as you feel is appropriate.
         'tags': ctx.tags,
@@ -933,8 +953,7 @@ async def on_client_connected(ctx: Context, client: Client):
         'permissions': get_permissions(ctx),
         'hint_cost': ctx.hint_cost,
         'location_check_points': ctx.location_check_points,
-        'datapackage_checksums': {game: game_data["checksum"] for game, game_data
-                                  in ctx.gamespackage.items() if game in games and "checksum" in game_data},
+        'datapackage_checksums': ctx.checksums,
         'seed_name': ctx.seed_name,
         'time': time.time(),
     }])
@@ -1940,25 +1959,11 @@ async def process_client_cmd(ctx: Context, client: Client, args: dict):
             await ctx.send_msgs(client, reply)
 
     elif cmd == "GetDataPackage":
-        exclusions = args.get("exclusions", [])
-        if "games" in args:
-            games = {name: game_data for name, game_data in ctx.gamespackage.items()
-                     if name in set(args.get("games", []))}
-            await ctx.send_msgs(client, [{"cmd": "DataPackage",
-                                          "data": {"games": games}}])
-        # TODO: remove exclusions behaviour around 0.5.0
-        elif exclusions:
-            exclusions = set(exclusions)
-            games = {name: game_data for name, game_data in ctx.gamespackage.items()
-                     if name not in exclusions}
-
-            package = {"games": games}
-            await ctx.send_msgs(client, [{"cmd": "DataPackage",
-                                          "data": package}])
-
-        else:
-            await ctx.send_msgs(client, [{"cmd": "DataPackage",
-                                          "data": {"games": ctx.gamespackage}}])
+        games = {
+            name: game_data for name, game_data in ctx.reduced_games_package.items()
+            if name in set(args.get("games", []))
+        }
+        await ctx.send_msgs(client, [{"cmd": "DataPackage", "data": {"games": games}}])
 
     elif client.auth:
         if cmd == "ConnectUpdate":
diff --git a/WebHostLib/customserver.py b/WebHostLib/customserver.py
index 4257c6aff3..2cade4960d 100644
--- a/WebHostLib/customserver.py
+++ b/WebHostLib/customserver.py
@@ -13,6 +13,7 @@ import threading
 import time
 import typing
 import sys
+from asyncio import AbstractEventLoop
 
 import websockets
 from pony.orm import commit, db_session, select
@@ -24,8 +25,10 @@ from MultiServer import (
     server_per_message_deflate_factory,
 )
 from Utils import restricted_loads, cache_argsless
+from NetUtils import GamesPackage
+from apmw.webhost.customserver.gamespackagecache import DBGamesPackageCache
 from .locker import Locker
-from .models import Command, GameDataPackage, Room, db
+from .models import Command, Room, db
 
 
 class CustomClientMessageProcessor(ClientMessageProcessor):
@@ -62,18 +65,39 @@ class DBCommandProcessor(ServerCommandProcessor):
 
 class WebHostContext(Context):
     room_id: int
+    video: dict[tuple[int, int], tuple[str, str]]
+    main_loop: AbstractEventLoop
+    static_server_data: StaticServerData
 
-    def __init__(self, static_server_data: dict, logger: logging.Logger):
+    def __init__(
+            self,
+            static_server_data: StaticServerData,
+            games_package_cache: DBGamesPackageCache,
+            logger: logging.Logger,
+    ) -> None:
         # static server data is used during _load_game_data to load required data,
         # without needing to import worlds system, which takes quite a bit of memory
-        self.static_server_data = static_server_data
-        super(WebHostContext, self).__init__("", 0, "", "", 1,
-                                             40, True, "enabled", "enabled",
-                                             "enabled", 0, 2, logger=logger)
-        del self.static_server_data
-        self.main_loop = asyncio.get_running_loop()
-        self.video = {}
+        super(WebHostContext, self).__init__(
+            "",
+            0,
+            "",
+            "",
+            1,
+            40,
+            True,
+            "enabled",
+            "enabled",
+            "enabled",
+            0,
+            2,
+            games_package_cache=games_package_cache,
+            logger=logger,
+        )
         self.tags = ["AP", "WebHost"]
+        self.video = {}
+        self.main_loop = asyncio.get_running_loop()
+        self.static_server_data = static_server_data
+        self.games_package_cache = games_package_cache
 
     def __del__(self):
         try:
@@ -83,12 +107,6 @@ class WebHostContext(Context):
         except ImportError:
             self.logger.debug("Context destroyed")
 
-    def _load_game_data(self):
-        for key, value in self.static_server_data.items():
-            # NOTE: attributes are mutable and shared, so they will have to be copied before being modified
-            setattr(self, key, value)
-        self.non_hintable_names = collections.defaultdict(frozenset, self.non_hintable_names)
-
     async def listen_to_db_commands(self):
         cmdprocessor = DBCommandProcessor(self)
 
@@ -118,42 +136,14 @@ class WebHostContext(Context):
             self.port = get_random_port()
 
         multidata = self.decompress(room.seed.multidata)
-        game_data_packages = {}
+        return self._load(multidata, True)
 
-        static_gamespackage = self.gamespackage  # this is shared across all rooms
-        static_item_name_groups = self.item_name_groups
-        static_location_name_groups = self.location_name_groups
-        self.gamespackage = {"Archipelago": static_gamespackage.get("Archipelago", {})}  # this may be modified by _load
-        self.item_name_groups = {"Archipelago": static_item_name_groups.get("Archipelago", {})}
-        self.location_name_groups = {"Archipelago": static_location_name_groups.get("Archipelago", {})}
-        missing_checksum = False
-
-        for game in list(multidata.get("datapackage", {})):
-            game_data = multidata["datapackage"][game]
-            if "checksum" in game_data:
-                if static_gamespackage.get(game, {}).get("checksum") == game_data["checksum"]:
-                    # non-custom. remove from multidata and use static data
-                    # games package could be dropped from static data once all rooms embed data package
-                    del multidata["datapackage"][game]
-                else:
-                    row = GameDataPackage.get(checksum=game_data["checksum"])
-                    if row:  # None if rolled on >= 0.3.9 but uploaded to <= 0.3.8. multidata should be complete
-                        game_data_packages[game] = restricted_loads(row.data)
-                        continue
-                    else:
-                        self.logger.warning(f"Did not find game_data_package for {game}: {game_data['checksum']}")
-            else:
-                missing_checksum = True  # Game rolled on old AP and will load data package from multidata
-            self.gamespackage[game] = static_gamespackage.get(game, {})
-            self.item_name_groups[game] = static_item_name_groups.get(game, {})
-            self.location_name_groups[game] = static_location_name_groups.get(game, {})
-
-        if not game_data_packages and not missing_checksum:
-            # all static -> use the static dicts directly
-            self.gamespackage = static_gamespackage
-            self.item_name_groups = static_item_name_groups
-            self.location_name_groups = static_location_name_groups
-        return self._load(multidata, game_data_packages, True)
+    def _load_world_data(self):
+        # Use static_server_data, but skip static data package since that is in cache anyway.
+        # Also NOT importing worlds here!
+        # FIXME: does this copy the non_hintable_names (also for games not part of the room)?
+        self.non_hintable_names = collections.defaultdict(frozenset, self.static_server_data["non_hintable_names"])
+        del self.static_server_data  # Not used past this point. Free memory.
 
     def init_save(self, enabled: bool = True):
         self.saving = enabled
@@ -185,34 +175,23 @@ def get_random_port():
     return random.randint(49152, 65535)
 
 
+class StaticServerData(typing.TypedDict, total=True):
+    non_hintable_names: dict[str, typing.AbstractSet[str]]
+    games_package: dict[str, GamesPackage]
+
+
 @cache_argsless
-def get_static_server_data() -> dict:
+def get_static_server_data() -> StaticServerData:
     import worlds
-    data = {
+
+    return {
         "non_hintable_names": {
             world_name: world.hint_blacklist
             for world_name, world in worlds.AutoWorldRegister.world_types.items()
         },
-        "gamespackage": {
-            world_name: {
-                key: value
-                for key, value in game_package.items()
-                if key not in ("item_name_groups", "location_name_groups")
-            }
-            for world_name, game_package in worlds.network_data_package["games"].items()
-        },
-        "item_name_groups": {
-            world_name: world.item_name_groups
-            for world_name, world in worlds.AutoWorldRegister.world_types.items()
-        },
-        "location_name_groups": {
-            world_name: world.location_name_groups
-            for world_name, world in worlds.AutoWorldRegister.world_types.items()
-        },
+        "games_package": worlds.network_data_package["games"]
     }
 
-    return data
-
 
 def set_up_logging(room_id) -> logging.Logger:
     import os
@@ -245,9 +224,18 @@ def tear_down_logging(room_id):
         del logging.Logger.manager.loggerDict[logger_name]
 
 
-def run_server_process(name: str, ponyconfig: dict, static_server_data: dict,
-                       cert_file: typing.Optional[str], cert_key_file: typing.Optional[str],
-                       host: str, rooms_to_run: multiprocessing.Queue, rooms_shutting_down: multiprocessing.Queue):
+def run_server_process(
+        name: str,
+        ponyconfig: dict[str, typing.Any],
+        static_server_data: StaticServerData,
+        cert_file: typing.Optional[str],
+        cert_key_file: typing.Optional[str],
+        host: str,
+        rooms_to_run: multiprocessing.Queue,
+        rooms_shutting_down: multiprocessing.Queue,
+) -> None:
+    import gc
+
     from setproctitle import setproctitle
 
     setproctitle(name)
@@ -263,6 +251,9 @@ def run_server_process(name: str, ponyconfig: dict, static_server_data: dict,
         resource.setrlimit(resource.RLIMIT_NOFILE, (file_limit, file_limit))
         del resource, file_limit
 
+    # prime the data package cache with static data
+    games_package_cache = DBGamesPackageCache(static_server_data["games_package"])
+
     # establish DB connection for multidata and multisave
     db.bind(**ponyconfig)
     db.generate_mapping(check_tables=False)
@@ -270,8 +261,6 @@ def run_server_process(name: str, ponyconfig: dict, static_server_data: dict,
     if "worlds" in sys.modules:
         raise Exception("Worlds system should not be loaded in the custom server.")
 
-    import gc
-
     if not cert_file:
         def get_ssl_context():
             return None
@@ -296,7 +285,7 @@ def run_server_process(name: str, ponyconfig: dict, static_server_data: dict,
         with Locker(f"RoomLocker {room_id}"):
             try:
                 logger = set_up_logging(room_id)
-                ctx = WebHostContext(static_server_data, logger)
+                ctx = WebHostContext(static_server_data, games_package_cache, logger)
                 ctx.load(room_id)
                 ctx.init_save()
                 assert ctx.server is None
diff --git a/apmw/__init__.py b/apmw/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/apmw/multiserver/__init__.py b/apmw/multiserver/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/apmw/multiserver/gamespackagecache.py b/apmw/multiserver/gamespackagecache.py
new file mode 100644
index 0000000000..c90200c744
--- /dev/null
+++ b/apmw/multiserver/gamespackagecache.py
@@ -0,0 +1,96 @@
+import typing as t
+from weakref import WeakValueDictionary
+
+from NetUtils import GamesPackage
+
+GameAndChecksum = tuple[str, str | None]
+ItemNameGroups = dict[str, list[str]]
+LocationNameGroups = dict[str, list[str]]
+
+
+K = t.TypeVar("K")
+V = t.TypeVar("V")
+
+
+class DictLike(dict[K, V]):
+    __slots__ = ("__weakref__",)
+
+
+class GamesPackageCache:
+    # NOTE: this uses 3 separate collections because unpacking the get() result would end the container lifetime
+    _reduced_games_packages: WeakValueDictionary[GameAndChecksum, GamesPackage]
+    """Does not include item_name_groups nor location_name_groups"""
+    _item_name_groups: WeakValueDictionary[GameAndChecksum, dict[str, list[str]]]
+    _location_name_groups: WeakValueDictionary[GameAndChecksum, dict[str, list[str]]]
+
+    def __init__(self) -> None:
+        self._reduced_games_packages = WeakValueDictionary()
+        self._item_name_groups = WeakValueDictionary()
+        self._location_name_groups = WeakValueDictionary()
+
+    def _get(
+        self,
+        cache_key: GameAndChecksum,
+    ) -> tuple[GamesPackage | None, ItemNameGroups | None, LocationNameGroups | None]:
+        if cache_key[1] is None:
+            return None, None, None
+        return (
+            self._reduced_games_packages.get(cache_key, None),
+            self._item_name_groups.get(cache_key, None),
+            self._location_name_groups.get(cache_key, None),
+        )
+
+    def get(
+        self,
+        game: str,
+        full_games_package: GamesPackage,
+    ) -> tuple[GamesPackage, ItemNameGroups, LocationNameGroups]:
+        """Loads and caches embedded data package provided by multidata"""
+        cache_key = (game, full_games_package.get("checksum", None))
+        cached_reduced_games_package, cached_item_name_groups, cached_location_name_groups = self._get(cache_key)
+
+        if cached_reduced_games_package is None:
+            cached_reduced_games_package = t.cast(
+                t.Any,
+                DictLike(
+                    {
+                        "item_name_to_id": full_games_package["item_name_to_id"],
+                        "location_name_to_id": full_games_package["location_name_to_id"],
+                        "checksum": full_games_package.get("checksum", None),
+                    }
+                ),
+            )
+            if cache_key[1] is not None:  # only cache if checksum is available
+                self._reduced_games_packages[cache_key] = cached_reduced_games_package
+
+        if cached_item_name_groups is None:
+            # optimize strings to be references instead of copies
+            item_names = {name: name for name in cached_reduced_games_package["item_name_to_id"].keys()}
+            cached_item_name_groups = DictLike(
+                {
+                    group_name: [item_names.get(item_name, item_name) for item_name in group_items]
+                    for group_name, group_items in full_games_package["item_name_groups"].items()
+                }
+            )
+            if cache_key[1] is not None:  # only cache if checksum is available
+                self._item_name_groups[cache_key] = cached_item_name_groups
+
+        if cached_location_name_groups is None:
+            # optimize strings to be references instead of copies
+            location_names = {name: name for name in cached_reduced_games_package["location_name_to_id"].keys()}
+            cached_location_name_groups = DictLike(
+                {
+                    group_name: [location_names.get(location_name, location_name) for location_name in group_locations]
+                    for group_name, group_locations in full_games_package.get("location_name_groups", {}).items()
+                }
+            )
+            if cache_key[1] is not None:  # only cache if checksum is available
+                self._location_name_groups[cache_key] = cached_location_name_groups
+
+        return cached_reduced_games_package, cached_item_name_groups, cached_location_name_groups
+
+    def get_static(self, game: str) -> tuple[GamesPackage, ItemNameGroups, LocationNameGroups]:
+        """Loads legacy data package from installed worlds"""
+        import worlds
+
+        return self.get(game, worlds.network_data_package["games"][game])
diff --git a/apmw/webhost/__init__.py b/apmw/webhost/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/apmw/webhost/customserver/__init__.py b/apmw/webhost/customserver/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/apmw/webhost/customserver/gamespackagecache.py b/apmw/webhost/customserver/gamespackagecache.py
new file mode 100644
index 0000000000..c58af4b4c6
--- /dev/null
+++ b/apmw/webhost/customserver/gamespackagecache.py
@@ -0,0 +1,42 @@
+from typing_extensions import override
+
+from NetUtils import GamesPackage
+from Utils import restricted_loads
+from apmw.multiserver.gamespackagecache import GamesPackageCache, ItemNameGroups, LocationNameGroups
+
+
+class DBGamesPackageCache(GamesPackageCache):
+    _static: dict[str, tuple[GamesPackage, ItemNameGroups, LocationNameGroups]]
+
+    def __init__(self, static_games_package: dict[str, GamesPackage]) -> None:
+        super().__init__()
+        self._static = {
+            game: GamesPackageCache.get(self, game, games_package)
+            for game, games_package in static_games_package.items()
+        }
+
+    @override
+    def get(
+        self,
+        game: str,
+        full_games_package: GamesPackage,
+    ) -> tuple[GamesPackage, ItemNameGroups, LocationNameGroups]:
+        # for games started on webhost, full_games_package is likely unpopulated and only has the checksum field
+        cache_key = (game, full_games_package.get("checksum", None))
+        cached = self._get(cache_key)
+        if any(value is None for value in cached):
+            if "checksum" not in full_games_package:
+                return super().get(game, full_games_package)  # no checksum, assume fully populated
+
+            from WebHostLib.models import GameDataPackage
+
+            row: GameDataPackage | None = GameDataPackage.get(checksum=full_games_package["checksum"])
+            if row:  # None if rolled on >= 0.3.9 but uploaded to <= 0.3.8 ...
+                return super().get(game, restricted_loads(row.data))
+            return super().get(game, full_games_package)  # ... in which case full_games_package should be populated
+
+        return cached  # type: ignore # mypy doesn't understand any value is None
+
+    @override
+    def get_static(self, game: str) -> tuple[GamesPackage, ItemNameGroups, LocationNameGroups]:
+        return self._static[game]
diff --git a/test/multiserver/__init__.py b/test/multiserver/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/multiserver/test_gamespackage_cache.py b/test/multiserver/test_gamespackage_cache.py
new file mode 100644
index 0000000000..440a46a08d
--- /dev/null
+++ b/test/multiserver/test_gamespackage_cache.py
@@ -0,0 +1,132 @@
+import typing as t
+from copy import deepcopy
+from unittest import TestCase
+
+from typing_extensions import override
+
+import NetUtils
+from NetUtils import GamesPackage
+from apmw.multiserver.gamespackagecache import GamesPackageCache
+
+
+class GamesPackageCacheTest(TestCase):
+    cache: GamesPackageCache
+    any_game: t.ClassVar[str] = "APQuest"
+    example_games_package: GamesPackage = {
+        "item_name_to_id": {"Item 1": 1},
+        "item_name_groups": {"Everything": ["Item 1"]},
+        "location_name_to_id": {"Location 1": 1},
+        "location_name_groups": {"Everywhere": ["Location 1"]},
+        "checksum": "1234",
+    }
+
+    @override
+    def setUp(self) -> None:
+        self.cache = GamesPackageCache()
+
+    def test_get_static_is_same(self) -> None:
+        """Tests that get_static returns the same objects twice"""
+        reduced_games_package1, item_name_groups1, location_name_groups1 = self.cache.get_static(self.any_game)
+        reduced_games_package2, item_name_groups2, location_name_groups2 = self.cache.get_static(self.any_game)
+        self.assertIs(reduced_games_package1, reduced_games_package2)
+        self.assertIs(item_name_groups1, item_name_groups2)
+        self.assertIs(location_name_groups1, location_name_groups2)
+
+    def test_get_static_data_format(self) -> None:
+        """Tests that get_static returns data in the correct format"""
+        reduced_games_package, item_name_groups, location_name_groups = self.cache.get_static(self.any_game)
+        self.assertTrue(reduced_games_package["checksum"])
+        self.assertTrue(reduced_games_package["item_name_to_id"])
+        self.assertTrue(reduced_games_package["location_name_to_id"])
+        self.assertNotIn("item_name_groups", reduced_games_package)
+        self.assertNotIn("location_name_groups", reduced_games_package)
+        self.assertTrue(item_name_groups["Everything"])
+        self.assertTrue(location_name_groups["Everywhere"])
+
+    def test_get_static_is_serializable(self) -> None:
+        """Tests that get_static returns data that can be serialized"""
+        NetUtils.encode(self.cache.get_static(self.any_game))
+
+    def test_get_static_missing_raises(self) -> None:
+        """Tests that get_static raises KeyError if the world is missing"""
+        with self.assertRaises(KeyError):
+            _ = self.cache.get_static("Does not exist")
+
+    def test_eviction(self) -> None:
+        """Tests that unused items get evicted from cache"""
+        game_name = "Test"
+        before_add = len(self.cache._reduced_games_packages)
+        data = self.cache.get(game_name, self.example_games_package)
+        self.assertTrue(data)
+        self.assertEqual(before_add + 1, len(self.cache._reduced_games_packages))
+
+        del data
+        if len(self.cache._reduced_games_packages) != before_add:  # gc.collect() may not even be required
+            import gc
+
+            gc.collect()
+
+        self.assertEqual(before_add, len(self.cache._reduced_games_packages))
+
+    def test_get_required_field(self) -> None:
+        """Tests that missing required field raises a KeyError"""
+        for field in ("item_name_to_id", "location_name_to_id", "item_name_groups"):
+            with self.subTest(field=field):
+                games_package = deepcopy(self.example_games_package)
+                del games_package[field]  # type: ignore
+                with self.assertRaises(KeyError):
+                    _ = self.cache.get(self.any_game, games_package)
+
+    def test_get_optional_properties(self) -> None:
+        """Tests that missing optional field works"""
+        for field in ("checksum", "location_name_groups"):
+            with self.subTest(field=field):
+                games_package = deepcopy(self.example_games_package)
+                del games_package[field]  # type: ignore
+                _, item_name_groups, location_name_groups = self.cache.get(self.any_game, games_package)
+                self.assertTrue(item_name_groups)
+                self.assertEqual(field != "location_name_groups", bool(location_name_groups))
+
+    def test_item_name_deduplication(self) -> None:
+        n = 1
+        s1 = f"Item {n}"
+        s2 = f"Item {n}"
+        # check if the deduplication is actually gonna do anything
+        self.assertIsNot(s1, s2)
+        self.assertEqual(s1, s2)
+        # do the thing
+        game_name = "Test"
+        games_package: GamesPackage = {
+            "item_name_to_id": {s1: n},
+            "item_name_groups": {"Everything": [s2]},
+            "location_name_to_id": {},
+            "location_name_groups": {},
+            "checksum": "1234",
+        }
+        reduced_games_package, item_name_groups, location_name_groups = self.cache.get(game_name, games_package)
+        self.assertIs(
+            next(iter(reduced_games_package["item_name_to_id"].keys())),
+            item_name_groups["Everything"][0],
+        )
+
+    def test_location_name_deduplication(self) -> None:
+        n = 1
+        s1 = f"Location {n}"
+        s2 = f"Location {n}"
+        # check if the deduplication is actually gonna do anything
+        self.assertIsNot(s1, s2)
+        self.assertEqual(s1, s2)
+        # do the thing
+        game_name = "Test"
+        games_package: GamesPackage = {
+            "item_name_to_id": {},
+            "item_name_groups": {},
+            "location_name_to_id": {s1: n},
+            "location_name_groups": {"Everywhere": [s2]},
+            "checksum": "1234",
+        }
+        reduced_games_package, item_name_groups, location_name_groups = self.cache.get(game_name, games_package)
+        self.assertIs(
+            next(iter(reduced_games_package["location_name_to_id"].keys())),
+            location_name_groups["Everywhere"][0],
+        )
diff --git a/test/webhost_customserver/__init__.py b/test/webhost_customserver/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/webhost_customserver/test_gamespackage_cache.py b/test/webhost_customserver/test_gamespackage_cache.py
new file mode 100644
index 0000000000..58ea2e37f9
--- /dev/null
+++ b/test/webhost_customserver/test_gamespackage_cache.py
@@ -0,0 +1,147 @@
+import typing as t
+from copy import deepcopy
+
+from typing_extensions import override
+
+from test.multiserver.test_gamespackage_cache import GamesPackageCacheTest
+
+import Utils
+from NetUtils import GamesPackage
+from apmw.webhost.customserver.gamespackagecache import DBGamesPackageCache
+
+
+class FakeGameDataPackage:
+    _rows: "t.ClassVar[dict[str, FakeGameDataPackage]]" = {}
+    data: bytes
+
+    @classmethod
+    def get(cls, checksum: str) -> "FakeGameDataPackage | None":
+        return cls._rows.get(checksum, None)
+
+    @classmethod
+    def add(cls, checksum: str, full_games_package: GamesPackage) -> None:
+        row = FakeGameDataPackage()
+        row.data = Utils.restricted_dumps(full_games_package)
+        cls._rows[checksum] = row
+
+
+class DBGamesPackageCacheTest(GamesPackageCacheTest):
+    cache: DBGamesPackageCache
+    any_game: t.ClassVar[str] = "My Game"
+    static_data: t.ClassVar[dict[str, GamesPackage]] = {  # noqa: pycharm doesn't understand this
+        "My Game": {
+            "item_name_to_id": {"Item 1": 1},
+            "location_name_to_id": {"Location 1": 1},
+            "item_name_groups": {"Everything": ["Item 1"]},
+            "location_name_groups": {"Everywhere": ["Location 1"]},
+            "checksum": "2345",
+        }
+    }
+    orig_db_type: t.ClassVar[type]
+
+    @override
+    @classmethod
+    def setUpClass(cls) -> None:
+        import WebHostLib.models
+
+        cls.orig_db_type = WebHostLib.models.GameDataPackage
+        WebHostLib.models.GameDataPackage = FakeGameDataPackage  # type: ignore
+
+    @override
+    def setUp(self) -> None:
+        self.cache = DBGamesPackageCache(self.static_data)
+
+    @override
+    @classmethod
+    def tearDownClass(cls) -> None:
+        import WebHostLib.models
+
+        WebHostLib.models.GameDataPackage = cls.orig_db_type  # type: ignore
+
+    def assert_conversion(
+        self,
+        full_games_package: GamesPackage,
+        reduced_games_package: dict[str, t.Any],
+        item_name_groups: dict[str, t.Any],
+        location_name_groups: dict[str, t.Any],
+    ) -> None:
+        for key in ("item_name_to_id", "location_name_to_id", "checksum"):
+            if key in full_games_package:
+                self.assertEqual(reduced_games_package[key], full_games_package[key])  # noqa: pycharm
+        self.assertEqual(item_name_groups, full_games_package["item_name_groups"])
+        self.assertEqual(location_name_groups, full_games_package["location_name_groups"])
+
+    def assert_static_conversion(
+        self,
+        full_games_package: GamesPackage,
+        reduced_games_package: dict[str, t.Any],
+        item_name_groups: dict[str, t.Any],
+        location_name_groups: dict[str, t.Any],
+    ) -> None:
+        self.assert_conversion(full_games_package, reduced_games_package, item_name_groups, location_name_groups)
+        for key in ("item_name_to_id", "location_name_to_id", "checksum"):
+            self.assertIs(reduced_games_package[key], full_games_package[key])  # noqa: pycharm
+
+    def test_get_static_contents(self) -> None:
+        """Tests that get_static returns the correct data"""
+        reduced_games_package, item_name_groups, location_name_groups = self.cache.get_static(self.any_game)
+        for key in ("item_name_to_id", "location_name_to_id", "checksum"):
+            self.assertIs(reduced_games_package[key], self.static_data[self.any_game][key])  # noqa: pycharm
+        self.assertEqual(item_name_groups, self.static_data[self.any_game]["item_name_groups"])
+        self.assertEqual(location_name_groups, self.static_data[self.any_game]["location_name_groups"])
+
+    def test_static_not_evicted(self) -> None:
+        """Tests that static data is not evicted from cache during gc"""
+        import gc
+
+        game_name = next(iter(self.static_data.keys()))
+        ids = [id(o) for o in self.cache.get_static(game_name)]
+        gc.collect()
+        self.assertEqual(ids, [id(o) for o in self.cache.get_static(game_name)])
+
+    def test_get_is_static(self) -> None:
+        """Tests that a get with correct checksum return the static items"""
+        # NOTE: this is only true for the DB cache, not the "regular" one, since we want to avoid loading worlds there
+        cks: GamesPackage = {"checksum": self.static_data[self.any_game]["checksum"]}  # noqa: pycharm doesn't like this
+        reduced_games_package1, item_name_groups1, location_name_groups1 = self.cache.get(self.any_game, cks)
+        reduced_games_package2, item_name_groups2, location_name_groups2 = self.cache.get_static(self.any_game)
+        self.assertIs(reduced_games_package1, reduced_games_package2)
+        self.assertEqual(location_name_groups1, location_name_groups2)
+        self.assertEqual(item_name_groups1, item_name_groups2)
+
+    def test_get_from_db(self) -> None:
+        """Tests that a get with only checksum will load the full data from db and is cached"""
+        game_name = "Another Game"
+        full_games_package = deepcopy(self.static_data[self.any_game])
+        full_games_package["checksum"] = "3456"
+        cks: GamesPackage = {"checksum": full_games_package["checksum"]}  # noqa: pycharm doesn't like this
+        FakeGameDataPackage.add(full_games_package["checksum"], full_games_package)
+        before_add = len(self.cache._reduced_games_packages)
+        data = self.cache.get(game_name, cks)
+        self.assert_conversion(full_games_package, *data)  # type: ignore
+        self.assertEqual(before_add + 1, len(self.cache._reduced_games_packages))
+
+    def test_get_missing_from_db_uses_full_games_package(self) -> None:
+        """Tests that a get with full data (missing from db) will use the full data and is cached"""
+        game_name = "Yet Another Game"
+        full_games_package = deepcopy(self.static_data[self.any_game])
+        full_games_package["checksum"] = "4567"
+        before_add = len(self.cache._reduced_games_packages)
+        data = self.cache.get(game_name, full_games_package)
+        self.assert_conversion(full_games_package, *data)  # type: ignore
+        self.assertEqual(before_add + 1, len(self.cache._reduced_games_packages))
+
+    def test_get_without_checksum_uses_full_games_package(self) -> None:
+        """Tests that a get with full data and no checksum will use the full data and is not cached"""
+        game_name = "Yet Another Game"
+        full_games_package = deepcopy(self.static_data[self.any_game])
+        del full_games_package["checksum"]
+        before_add = len(self.cache._reduced_games_packages)
+        data = self.cache.get(game_name, full_games_package)
+        self.assert_conversion(full_games_package, *data)  # type: ignore
+        self.assertEqual(before_add, len(self.cache._reduced_games_packages))
+
+    def test_get_missing_from_db_raises(self) -> None:
+        """Tests that a get that requires a row to exist raise an exception if it doesn't"""
+        with self.assertRaises(Exception):
+            _ = self.cache.get("Does not exist", {"checksum": "0000"})