I had that happen with a few rpgm games i remember Nymphomania priestess running like ass in the earlier versions and futa family has the puzzle room in the castle that frame rate plummets to game breaking levels and there was a harem game that can't remember that runs like shit, i don't really see a game that majority of the game is 2d excluding the sex scenes should run poorly like at all my computer is held together by chewing gum and ducttape and i get unreal 4 engine game running terribly but i have gotten games like koikatsu to run fine but something like love & sex to be unplayable, i have played the recent update because i am gonna wait until when ever kana gets fucked by the futa and hopefully by than whatever lag there is probably be fixed because demo ran poorly but to be fair summertime saga also ran like shit too early and crashed alot and now it runs fine now .