User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0 Build ID: 20180517114003 Steps to reproduce: I've opened Firefox and opened some websites. Then I've created new window in *same* firefox process and opened same page Actual results: Fonts in second window are blurry. This includes fonts in the UI - see tab title. I'll attach screenshots of this - both screenshots are made from same FF process, just different windows. Difference in rendering can be easily seen. Expected results: Fonts should render well and new windows should not be different. I should point out that it looks like there is no such problem when several windows get restored on Firefox start up - it looks like problem only occurs when new window is opened some time after using Firefox.

Hello Nikolay, I have attempted reproducing this issue on Ubuntu 16 and 17 but I could not reproduce it with the information I have here. I tried reproducing it on different sections of the Cursera website, but no such reproduction was observed. Please download Firefox Nightly from here: https://nightly.mozilla.org/, retest the problem and, hopefully, try and give some more details on the steps to reproduce.

Thanks for your response! So I did some more investigation. It looks like this is caused by 'layers.acceleration.force-enabled' config parameter that I have set to true. So on nightly from PPA with a single page opened (https://www.coursera.org/learn/nlp-sequence-models?recoOrder=7&utm_medium=email&utm_source=recommendations&utm_campaign=Oc6xEF0_EeiWLetO06Kdhw) I can reproduce the problem: window restored looks fine, new window created after browser started up looks blurry I have Nvidia graphics card with Nvidia proprietary driver - not sure if that affects anything. Please let me know if more information is needed. Thanks!

Could not confirm the reproduction of this issue. It may only be reproducible on Nvidia hardware, which do not have on my Linux test machines. I am setting this bug's component as Graphics: Layers and let developers decide whether this needs to be addressed separately from the other related issues.

Update: Lately (including currently nightly) this happens even on a first window right after browser starts up - all text including UI is very blurred. This makes acceleration pretty much unusable. Is there any additional information I can provide to help to resolve this issue? Thanks!

I think I may have found the problem. It looks like I had FXAA enabled accidentally and that seems to caused that. So maybe this is indeed not a FF problem. Sorry for the bother.