You mean simply having Rosetta installed on your machine noticeably slows down everything else, even if you're not using an app under Rosetta? This sounds like a bug.
probably. but the difference in performance for IntelliJ was night and day, and given the inability to uninstall rosetta and AB test I don’t really want to play with it again.
I recently had to wipe my machine to remove Rosetta (there's no "uninstall"), and saw quite a significant boost in performance across the board.