FastAssetBundleLoader

Game loads faster with large size mods by caching asset bundles.

It speeds up repeated mod startup by caching slow asset bundles into reusable files under BepInEx/cache. The implementation is based on the same general approach as DiFFoZ's BepInExFasterLoadAssetBundles, but is adapted and trimmed for this Valheim-focused project. https://thunderstore.io/c/lethal-company/p/DiFFoZ/BepInEx_Faster_Load_AssetBundles_Patcher/

What it does

• It caches Valheim mod asset bundles that are stored in LZ4HC format into reusable LZ4 cache files, so subsequent loads can be faster.
• This is patcher.dll so it needs to be placed in BepInEx/patchers folder

Cache behavior

• Cache files are stored under BepInEx/cache/ValheimFasterLoadAssetBundles by default.
• Cache files are created only when eligible asset bundles are actually loaded.
• A single run may not warm every cache entry if the game is closed before the background queue finishes or if some bundles are loaded only in specific scenes. Later runs may therefore become faster.
• For a broader warm-up, enter a world instead of stopping at the lobby and keep the game running until cache activity settles. Different gameplay paths may create additional entries, so caching every installed asset bundle is not guaranteed.
• Cache could take up to few GB of your disk space according to the mods you are using. (More than 3GB in my case)
• The main measured benefit is repeated loading to the lobby. Improvements from lobby to world depend on which eligible bundles are loaded and may not be noticeable in every setup.

Other mods to run the game faster

• StartupAccelerator
• LocalizationCache

I have tested with following combination to measure loading time.

• Modpack only = 246s
• FastAssetBundleLoader + Modpack = 170s
• StartupAccelerator + Modpack = 202s
• LocalizationCache + Modpack = 218s
• FastAssetBundleLoader + LocalizationCache + Modpack = 145s
• FastAssetBundleLoader + StartupAccelerator + Modpack = 127s

StartupAccelerator is faster but some mods might not work properly with it.

Changelog

1.0.3

• Moved FastAssetBundleLoader.dll into the patchers/ directory in both Thunderstore and Nexus archives so they can be extracted directly into the BepInEx directory.

1.0.2

• Cache regeneration is recommended after updating: close the game, delete only BepInEx/cache/ValheimFasterLoadAssetBundles, and let eligible bundles rebuild as they are loaded.
• The first run may not warm every cache entry. Enter a world and allow cache activity to settle; later runs or different gameplay paths may create additional entries.

1.0.1

• Refactored the asset bundle cache pipeline and runtime hooks for safer cache reuse.
• Improved cache metadata validation, cleanup, and failure handling.
• Clarified cache warm-up behavior, including when entering a world or additional runs may create more entries.
• Added reproducible standalone Thunderstore and Nexus release packaging.

1.0.0

• Initial release.