User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0) Gecko/20100101 Firefox/63.0 Build ID: 20180728101501 Steps to reproduce: create new profile. Enable WR Open https://bugzilla.mozilla.org/attachment.cgi?id=8995714 scroll with the mouse Actual results: poor janky scrolling https://perfht.ml/2NSsPvP Expected results: not so non-WR is pretty smooth

see also: bug 1479196

confirmed

From the profile it looks like the renderer thread is swamped. So bug 1480317 would help.

I don't think this needs to block release

the testcase has started to act a bit weird. Now it takes 2GB memory to display with tons of CPU

It now scrolls better than what I remember it used to : https://perfht.ml/2L7Knnb

The new profile in comment 6 shows better behaviour than before, but still shows long composites (upwards of 60ms). 3% of time on the renderer thread is in NtQueryLicenseValue much like your other profiles. But this time 7% is in draw_elements_instanced so there might be something we can improve here.

(In reply to Kartikaya Gupta (email:kats@mozilla.com) from comment #7) >3% of time on the renderer thread is in NtQueryLicenseValue much like your other profiles. But this time >7% is in draw_elements_instanced so there might be something we can improve here. Anecdotally, the last round of reducing mem_cpy work on the WR side reduced the time spent in NtQueryLicenseValue in general on all pages.

This is a UTF encoded emoji page, that will show actual emojis in proper rows and columns. This still scrolls with jank and checkerboard with the latest patch from bug 1493353 applied. Bug 1493353 did fix the original testcase from #comment 0

Mayank, can you post of a profile?

of course, feel free to WONTFIX this, as its terribly artificail.