User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:46.0) Gecko/20100101 Firefox/46.0 Build ID: 20160503215307 Steps to reproduce: Updated Firefox to 47.0 within Arch Linux 64 bit. Also tried Firefox downloaded from Mozilla site instead of Arch Linux package, got similar result (so not posting bug for the package but for Firefox itself). Disabling hardware acceleration did not help me. Downgrading to Firefox 46.0.1 solved the issue, 46.0.1 works smoothly. My system is: 4.6.1-2-ARCH #1 SMP PREEMPT Thu Jun 2 15:46:17 CEST 2016 x86_64 GNU/Linux Actual results: Keyboard input is very laggy. It hangs up for several seconds then processes queued events. With both Arch Linux package and binary archive from mozilla.org, with both hardware acceleration on and off. This makes typing almost impossible. Not only typing, but also hotkeys lag. Mouse events are handled quickly. Expected results: I guess it should handle typing correctly =)

Also tried restarting without addons and starting with clean profile -- got no effect, it still lags.

It's probably a dupe of bug 1279505 or very similar. Could you type about:config in the location bar and set gfx.xrender.enabled to true, then restart Firefox to apply. Is it better?

It was already true, but yes, I had used i3wm. Switched to xfce, Firefox works nocely now. So is it i3wm bug?

Under lxde it works great too

Thanks for the feedback. As it worked in 46, there is probably a regression in 47. Could you install the tool Mozregression to narrow down a regression range. See http://mozilla.github.io/mozregression/ for details. As 46 works, enter "mozregression --good=46" then copy here the final pushlog (from repo mozilla-inbound).

Hello again. I am very sorry. I have even installed mozregression and was going to use it. But short time before I have updated system again (you know, it is heritable disease for us, Arch Linux users %)) and issue has gone. Firefox is 47.0 as before, but I have updated kernel and number of other packages and Firefox works pretty well now. I will definitely use mozregression in case I get such an issue again. And sorry again for disturbing you all and then missing this catch =(...

Based on Comment 6, setting the status to Resolved Worksforme. Reporter, please feel free to reopen it if the issue is back and reproducible.