I actually didn't think to consider Chromebooks at all! That does sound like an annoying problem, I think it might be some quirk with how ChromeOS detects mouse capturing. I'll try to look into it a bit and see if I can figure out the issue.
I'm not sure why no devs talk about it, but it's surprisingly hard to figure out if the player wants the mouse cursor to be captured or not in code, and then do capture it or make it visible, and have it work the same way for all browsers and OSs.
Also, can I ask what sort of performance you're getting? I'm also guessing you're using lowest video settings already as well? I have some ideas to improve performance on lower end systems, but it'll likely not be ready until the next update, and I also can't promise if it will help a lot.
