Talos has detected a Firefox performance regression from push: https://hg.mozilla.org/integration/autoland/pushloghtml?changeset=562966f195b0f071cf1d973f7b4fd51ec8594343 As author of one of the patches included in that push, we need your help to address this regression. Regressions: 4% tart osx-10-10 opt e10s stylo 8.35 -> 8.71 3% tart linux64 opt e10s stylo 2.28 -> 2.34 2% tart linux64 pgo e10s stylo 2.07 -> 2.11 You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=11937 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

It's clear a perf regression got in. Bad news is I'm not certain regarding the source of it, because of the noisy results. It seems to me that this regression increased in 2 steps, through 2 separate bugs. These landed at a 3 hour difference. Namely, bug 1436361 and bug 1442651. This seems to makes sense, as the bugs are related to the tab mechanism. ::dao What do you think?

It looks like these numbers have recovered?

(In reply to Ryan VanderMeulen [:RyanVM] from comment #2) > It looks like these numbers have recovered? Yes, I agree.