So I've been keeping an eye on CPU usage on my netbook. Wondered why Firefox behaved so erratically in that regard. Experimented a bit, found out I can max out my quadcore 2.2GHz Turboboosted intel CPU by moving the mouse cursor in small circles over the Firefox main window.

So I researched a bit.
Found this bug from two months ago, apparently I'm not the only one to notice that issue:
https://bugzilla.mozilla.org/show_bug.cgi?id=1427113Status still left at unconfirmed despite copious amounts of evidence and devs coming in and explaining the why's and how's.
I just love the reasoning...
Overall around 30% of the time in the main thread seems to be spent processing mouse events (~12% in APZ processing, ~17% in dispatching to content) which does seem fairly high.
We use MousePosTracker to move the status panel (that displays link URLs) to the other side when the mouse pointer is close. We listen to mousemove events before we even display the status panel, so that we already know the pointer position when we want to display the panel. I'm not sure how this could be optimized away without compromising the UX.

THEY ARE FUCKING DISPATCHING MOUSE MOVEMENT EVENTS FROM WINDOWS... IN JAVASCRIPT. NO FILTERING, NO THROTTLING. Sorry not sorry for caps. That idea is just too outlandish to parse, it broke my brains. And it's by design and they seem unwilling to fix it.

Because they want their shitty ass tiny unusable crippled to fuck status bar to hide away from the mouse cursor. Without an option to hide it or make it always-on or otherwise customize it because webextensions are a piece of rotting horse manure that can't support downthemall, reload on fail, and a whole hogload of my other important extensions that I only needed in the first place because Opera jumped off a cliff and died when they switched engines.
Fuck me, what an incredibly stupid way to waste CPU cycles. Each and every freaking time your mouse moves a subpixel. Not gonna waste battery on such idiocy. Time to download vivaldi. Firefox Quantum can eat a dick.
