I use Affinity Designer and Photo and they are very fast even at huge sizes (I do art). But they don't listen to user feedback or suggestions much if at all. AD/P can use OpenGL Vulcan or Metal (I use Metal) and it's amazingly fast for most operations. I also use Artrage 5 and it's abysmally slow probably not optimized for any platform either, probably not much different from Inkscape (though mostly bitmap drawing).