Using Firefox 38.0.5. I’ve had this problem for a long time.
Mostly it shows up in the address bar or search box. The white display will show pixelation or glitches or blotches or something. If you roll over them with the cursor, they go away.
I don’t remember ever seeing this in another context on the computer, but I can’t swear it. I use Chrome, too, and don’t remember seeing it there.
Thoughts?
Maybe turn off hardware acceleration? Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems | Firefox Help
It seems like the kind of artifact that happens when the GPU is rendering something and getting glitchy, maybe due to it overheating a bit or whatever.
The impact on your browsing experience should be minimal.
Thank you! That seems to have helped or fixed it. It amazes me how annoying I find that sort of glitch.
Thank you again!
I hope it does! It’s sporadic, so I guess you won’t know until a few days later.
By the way, thanks for posting such an excellent screenshot. Very clear 
