Talos has detected a Firefox performance regression from push: https://hg.mozilla.org/releases/mozilla-beta/pushloghtml?changeset=652cff2a5a79e299ee7d34ca0bb9703de01e98fe As author of one of the patches included in that push, we need your help to address this regression. Regressions: 76% displaylist_mutate windows7-32 opt e10s stylo 4,191.12 -> 7,362.65 74% displaylist_mutate linux64 opt e10s stylo 2,686.70 -> 4,679.81 67% displaylist_mutate windows10-64 opt e10s stylo 3,674.61 -> 6,152.29 61% displaylist_mutate osx-10-10 opt e10s stylo 6,865.82 -> 11,074.49 Improvements: 3% stylebench windows10-64 opt e10s stylo 70.09 -> 72.37 You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=12805 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

:mattwoodrow Out of the big patch that landed, bug 1454509 looks like the source of regression. Please state whether I'm right or wrong. Assuming I got this right, I guess we simply have to accept this, right? (according to [1]) [1] https://bugzilla.mozilla.org/show_bug.cgi?id=1454509#c0

Yes, unfortunately we do. Retained-dl is the source of the wins, so disabling it means we lose them. 61 will be better!