Perfherder has detected a raptor performance regression from push 7b2f3b4b6afa10365955bbbb336587df099d7aae. As author of one of the patches included in that push, we need your help to address this regression.

Regressions:

6% raptor-tp6-twitch-firefox-cold loadtime windows10-64-shippable-qr opt webrender 1,001.18 -> 1,064.50

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests. Please follow our guide to handling regression bugs and let us know your plans within 3 business days, or the offending patch(es) will be backed out in accordance with our regression policy.

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Bug 1654369 merely moves a pref assignment from firefox.js to all.js to enable the feature controlled by the pref on all platforms (including GeckoView).

The reported regression is on Windows load time, which is not affected at all by the change, since the pref was set to the same value before via firefox.js on desktop.

Matt, do you know what is going on, do raptor tests not use firefox.js?

From looking at the graph I think bug 1654357 is more likely to blame. The regression clearly started before this landing and as Eugen said, this change shouldn't have affected desktop Firefox.

Andra, what do you think about moving the blame to one of the earlier commits where the graph first showed the increase?

Sorry for the confusion, marking this as a duplicate of Bug 1654357