The real regression seems to have appeared on `autoland` around August 2. Skimming over the talos perf regressions which appeared around that time, I've come across bug 1572682. That bug has 2 regressions of the same magnitudes; it landed a fix around August 12, which canceled this regression also.
Bug 1572674 Comment 9 Edit History
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The real regression seems to have appeared on `autoland` around August 2. Skimming over the talos perf regressions which appeared around that time, I've come across bug 1572682. That bug has 2 different regressions of the same magnitudes; it landed a fix around August 12, which canceled this regression also.