Talos has detected a Firefox performance regression from push: https://hg.mozilla.org/releases/mozilla-beta/pushloghtml?changeset=f8c381b7d9a42ecbe4ed34792cd98430b32b6dd0 As author of one of the patches included in that push, we need your help to address this regression. Regressions: 164% ts_paint_webext linux64 opt e10s stylo 195.25 -> 516.08 110% ts_paint linux64 opt e10s stylo 191.50 -> 402.92 108% ts_paint_heavy linux64 opt e10s stylo 198.08 -> 412.50 5% sessionrestore_no_auto_restore linux64 opt e10s stylo282.58 -> 297.47 5% sessionrestore linux64 opt e10s stylo 242.58 -> 254.92 You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=13432 On the page above you can see an 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(s), please see: https://wiki.mozilla.org/Buildbot/Talos/Tests For information on reproducing and debugging the regression, either on try or locally, see: https://wiki.mozilla.org/Buildbot/Talos/Running *** Please let us know your plans within 3 business days, or the offending patch(es) will be backed out! *** Our wiki page outlines the common responses and expectations: https://wiki.mozilla.org/Buildbot/Talos/RegressionBugsHandling

The patch that caused this only deactivated a flag. To the looks of it, this canceled the "wins" from bug 1447719. If I'm right about this connection, then this regression is harmless.

That's exactly correct. This feature is behind the EARLY_BETA_OR_EARLIER ifdef on Linux, per the below commit: https://hg.mozilla.org/mozilla-central/rev/c5980d2f915f It's a valid regression, but expected and one we don't intend to address in 61.