Config File

OaT's mixins (the patches it applies to Minecraft and to other mods) are controlled by config/optimizationsandtweaks-mixins.cfg.

This replaced the old system of one boolean per mixin in optimizationsandtweaks.cfg. The Mixin enum in the source code is now the single source of truth for which patches exist; this file only carries your overrides, resolved at startup by MixinConfigResolver. (If you are upgrading, your old per-mixin booleans are imported automatically once — the migratedFromLegacyConfig flag.)

Two ways to turn mixins off

1. By category (broad)

The categories { } section has one boolean per group of mixins. Set a group to false to disable it:

categories {
    B:client=true      # client-side rendering tweaks
    B:common=true      # common (both sides) core tweaks
    ...                # one toggle per category, each with an inline comment
}

2. By individual mixin (surgical — crash bisecting / opting out of a single patch)

The advanced { } section forces a specific mixin off (or on) by its exact Mixin enum entry name, regardless of its category toggle:

advanced {
    # force these OFF (e.g. bisecting a crash or a mod incompatibility)
    S:disabledMixins <
        client_core_MixinRenderBlocks
        common_core_MixinDataWatcher
    >
    # force these ON (override a disabled category)
    S:forceEnabledMixins <
    >
}

Entry names follow common|client|server_<area>_Mixin<Target> (they match the Mixin enum in the source). OaT logs the resolved enable/disable set at startup, so you can confirm what actually applied.

Standalone (non-mixin) options

A handful of genuinely standalone options remain in optimizationsandtweaks.cfg (these are NOT per-mixin toggles — those all moved to the file above): the CPU count for the async features, the Rust pathfinding / profiler / panic-guard flags, the Thaumcraft aspect-cache, FML auto-confirm, the Tidy-Chunk backport, and a few debuggers. Each has an inline comment. All are read once at startup, so a change takes effect on the next full Minecraft restart.