Client side FPS optimization mod that skips collision checks on the client's render thread because these check are already handled by the server. FPS currently suffers because the client calculates collisions for seen and unseen entities. When a lot of entities are present and tightly packed together, this issue is far more severe. Running this mod, expect an FPS improvement in areas with loads of entities. Below is a video showing the FPS difference of removing these collision checks on my PC. This mod aims to fix: https://bugs.mojang.com/browse/MC-228976 which has been confirmed on the bug tracker via community consensus.
Forge: https://www.curseforge.com/minecraft/mc-mods/entity-collision-fps-fix
Video showcase: