User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:65.0) Gecko/20100101 Firefox/65.0 Steps to reproduce: For example having uBlock Origin and Bitwarden installed. Have gfx.webrender.all enabled. Open their widget by clicking on the respective icon in the symbol bar. Actual results: The widgets open really slowly. It's like that for quite some time now. Expected results: The widgets should open without delay.

Hi, I cannot reproduce the issue on macOS 10.14 using the latest Nightly 65.0a1 (20181114100226). There is a slight delay between the clicking on the Bitwarden widget and opening it, but couldn't notice any difference with webrender enabled/disabled nor with the other add-on you've mentioned. Due note that I was trying to reproduce the issue with a clean profile, only with the two mentioned add-ons active. Could you please retest using safe mode (https://goo.gl/AR5o9d), maybe even a new clean Firefox profile (https://goo.gl/AWo6h8), to eliminate add-ons or custom settings as a possible cause?

I tried with all add-ons disabled except these two -- it's the same for me. With webrender enabled there's a noticably bigger delay with widget rendering. I'm not sure what to test in safe mode as all extensions get disabled then. The delay is most noticable wirh uBlock origin. But bitwarden feels also slower.

Could you give us a screen recording to have a better overview about the situation?

I hope the attached screen recordings explain what I mean.

This might be related to bug 1437556.

I'm assigning the same component as the bug mentioned in comment 7 to involve the development team and get an opinion on this.