This is mostly an issue with the resolution that we used for the textures, along with having a lot of different textures for different body parts. We're going to try and work on this before the release of the full game, and I'm going to do testing on weaker hardware that I have lying around.
I may update this game before the full game with performance fixes, so more people can test it.
My personal projects shouldn't have this issue as well, as most of the issues are art-related. Future projects ideally run better than Feraline, not worse.