Created attachment 617253 [details] [diff] [review] patch I'd like to try something like this. Basically split the slowest forget skippable to two parts. Would have to look at telemetry data to see how this affects to max forgetSkippable times, and whether CC times are affected too.
Comment on attachment 617253 [details] [diff] [review] patch Looks reasonable. Are the max forget skippable times in telemetry actually bad? Have you tried profiling to see how much each of these things you are splitting up takes?
UnmarkGrayJSListenersInCCGenerationDocuments and xpc_UnmarkSkippableJSHolders tend both to be somewhat slow, at least when I have lots of tabs open. But I'll do some profiling again (haven't done any for few weeks).
Backed out in order to investigate Bug 749461 https://hg.mozilla.org/mozilla-central/rev/0aa393eef856
Based on the initial telemetry data, the patch doesn't affect too much to the already low median times, but helps significantly with the worst 5%, so mean time decreases quite nicely.