Regarding the screen shaking, it seems to be due to the browser’s graphics acceleration (you have to enable it)… but it appears right from the start. I’ve tried several times and it’s never happened to me in the middle of a game.
Viewing post in Cyber Pet'scape - V.0.02 jam comments
In case it helps investigate further, the screen shake did not start from the beginning. I was able to play and everything was smooth at the beginning. Everything started at the same time, screen shake, music stop, huge lag. I had been playing for a while but couldn’t anymore after this and I couldn’t reach the boss.