What this mod does
BadOptimizations is a client-side Minecraft modification created by thosea. It targets parts of the game engine outside of standard block and entity rendering. Instead of rewriting large rendering pipelines, it applies smaller performance adjustments across tick routines.
The project runs on the client only. You can't install it on a dedicated server because server environments are unsupported. It works with Fabric and Neoforge. Supported Minecraft versions include 26.3, 26.2, 26.1.2, 26.1.1, 26.1, 1.21.11, and 1.21.10. You don't need extra library dependencies to use it. The code is licensed under the MIT License.
Targeted optimizations
The mod adjusts several specific routines in the client tick.
First, it stops unnecessary lightmap texture updates. In vanilla Minecraft, the client runs vector math during every tick to calculate sky and block lighting, then uploads that new texture to the GPU. This mod caches that texture. It skips updates whenever conditions affecting brightness, such as the gamma slider or potion effects, stay unchanged.
Second, it controls debug logic. The base game contains four debug renderers for bees, game events, game tests, and villager AI. Vanilla runs the logic for these renderers even when there's no incoming data to process. BadOptimizations executes them only if debug mode is active and the server sends data.
Third, it simplifies sky color math on version 1.21.10 and below. Vanilla samples surrounding biomes with a loop that runs 216 times every frame. Real talk, badOptimizations only uses that full color sampler when you stand between biomes that have different sky colors, caching the result each tick. Otherwise, it uses a shorter and faster sky color calculation.
Compatibility and settings
You can disable any single optimization in the configuration file if you need to troubleshoot an issue.
Other developers can mark their mods as incompatible with specific BadOptimizations features. When the game detects those mods, BadOptimizations disables the conflicting option automatically. Developers can also add hooks to signal when the sky color or lightmap needs a fresh update instead of disabling features entirely.
Test results
Performance gains depend on your hardware and setup. The author tested the mod on a computer with an Intel i7 12700 processor, an RTX 3060 graphics card, and 4GB of allocated RAM running the Fabulously Optimized modpack.
Without toast popups, frame rates rose from 1926-1955 FPS to 2008-2023 FPS. With toasts active, frame rates increased from 1351-1384 FPS to 1414-1458 FPS.