This wouldn't really be categorized as a bug, but it bugs me personally. The login and register screen takes a massive toll on the frames per second even on my stationary PC. I assume this is due to the background video rendering. The old more simple layout login screen did not have any of these issues, which I would personally prefer. My suggestion would be to either use a still background, or optimizing it lowering the resolution (which probably wouldn't hurt as it is blurred out anyway). This is more of a suggestion that I hope you can use. Sorry for the block of text.