On any version before the snapshot 20w22a, I get approximately 250 frames per second on average, whereas on 20w22a, I get around 35 frames per second (with all of the same settings, and nothing built in the world). I've tried using different worlds, as well as new worlds, and have gotten the same results every single time. I highly recommend completely scrapping the experimental rendering changes, because the old graphics were completely fine, and didn't have any performance issues, unlike these new graphics that completely ruin the game.