Perf is a real command[]
It is added in the latest 1.17 pre-release: See: https://www.minecraft.net/en-us/article/minecraft-1-17-pre-release-1#:~:text=DEDICATED%20SERVER%20PERF,the%20recording%20early.
--SuperDragonXD1 (talk) 06:24, 29 May 2021 (UTC)