scroll bug
Rendering and the scroll event lag when scrolling the page. Enabling/disabling smooth scrolling feature doesn't affect this. Opening the Firebug fixes it and the lag disappears. See example https://jsfiddle.net/p2p95asn/ the head will flutter when you try to scroll the page, but with the Firebug opened it will work smoothly.
Opaite Mbohovái (1)
Hi ! Looking for a proper solution I've come across numerous of the same complaints, and all kinds of different solutions to the problem.
I'm just going to ask you to take a look at this thread :
https://support.mozilla.org/en-US/questions/1157085
And this article :
https://www.in8sworld.net/blog/archives/4800
As for Firebug : you probably already know this, but just in case :