Talos has detected a Firefox performance regression from your commit 462a51797af1901934d422606a6a090cdb96bab0 in bug 1226118. We need you to address this regression. This is a list of all known regressions and improvements related to your bug: http://alertmanager.allizom.org:8080/alerts.html?rev=462a51797af1901934d422606a6a090cdb96bab0&showAll=1 On the page above you can see Talos alert for each affected platform as well as a link to a graph showing the history of scores for this test. There is also a link to a treeherder page showing the Talos jobs in a pushlog format. To learn more about the regressing test, please see: https://wiki.mozilla.org/Buildbot/Talos/Tests#tp5o_scroll Reproducing and debugging the regression: If you would like to re-run this Talos test on a potential fix, use try with the following syntax: try: -b o -p linux64,win64,win32 -u none -t g1,g1-e10s # add "mozharness: --spsProfile" to generate profile data To run the test locally and do a more in-depth investigation, first set up a local Talos environment: https://wiki.mozilla.org/Buildbot/Talos/Running#Running_locally_-_Source_Code Then run the following command from the directory where you set up Talos: talos --develop -e <path>/firefox -a tp5o_scroll Making a decision: As the patch author we need your feedback to help us handle this regression. *** Please let us know your plans by Monday, or the offending patch will be backed out! *** Our wiki page outlines the common responses and expectations: https://wiki.mozilla.org/Buildbot/Talos/RegressionBugsHandling

in fact in compare view I found a few others which are suspect: https://treeherder.mozilla.org/perf.html#/compare?originalProject=mozilla-inbound&originalRevision=f3741d47fb6b&newProject=mozilla-inbound&newRevision=462a51797af1&showOnlyConfident=1 specifically all the tp5o scroll tests, and tsvg opacity: https://treeherder.mozilla.org/perf.html#/graphs?timerange=604800&series=[mozilla-inbound,505e97c4c50669524afd8d210471ceddf62cfe2a,1]&highlightedRevisions=f3741d47fb6b&highlightedRevisions=462a51797af1

I have done a lot of retriggers on all the jobs to boost confidence in the regressions. It looks like :birtles is aware of this already (https://bugzilla.mozilla.org/show_bug.cgi?id=1226118#c50) :) :birtles, can you help us understand what is going on here and don't be shy to ask questions :) There are a lot of patches, I can bisect them on try if each is atomic.

I'm looking into this in bug 1230448.