Sorry guys. It seems some systems have trouble with the animations. The only thing that changed this update was that I updated the version of Renpy to the newest one. The animations are WebM vp9 (vp8 for android), like any other game. If the next Renpy update doesn't fix it, I may have to release a compressed version with 30 fps videos for the people having problems.
It is definitely the decoding. I am 100% shure of that. Currently using and old PC, which runs fine on linux, but youtube videos with vp's sometimes gives me some stuttering. So I started to use firefox extension to force h264-decoding. Much better than it was before. So it is definitely the codec. Would be nice for you to make compressed version for ppl like me (and many other here as well).