There is a massive performance regression in the snapshots 21w37a and 21w38a, which does not happen on 1.17.1.

Depending on what you are doing in-game frametimes can be easily 30 to 40 ms more than the worst case on 1.17.1, resulting in about half the average FPS during normal gameplay compared to 1.17.1 on my setup.

GPU utilization is about the same (at max ~ 35%) in all tested versions.

I was not able to test each version on the exact same map due to seed weirdness, so 1.17.1 is in a different spot, but one that should be even more GPU heavy than the scene in the snapshots, yet performs way better.