If a windmill is built using the sail blocks, players with enabled shaders (Complementary Shader 4.1 for me) are experiencing a huge hit on the game performance. Some players report, that if wool blocks instead of sail blocks are getting used, the performance isn't influenced. This wasn't tested by me, tho.

The performance goes back to normal as soon as the windmill is deactivated. Stationary sail blocks do not impact the performance.

Tested on Minecraft 1.16.5, Forge 36.2.0, Optifine HD8_U_G8, Create v0.3.2b.

#1202