This is some kind of undocumented API for mac OS which allows us to disable event logging, I believe. http://searchfox.org/mozilla-central/rev/61054508641ee76f9c49bcf7303ef3cfb6b410d2/widget/cocoa/nsAppShell.mm#335 This was added as a workaround to security bug 1092855. It appears, however, that this was fixed in an update to OS X 10.10.2: https://bugzilla.mozilla.org/show_bug.cgi?id=1092855#c200 (see http://support.apple.com/en-us/HT204244 in particular). Here's a profile where it shows us waiting for 34ms before first paint to talk to this API: https://perfht.ml/2s6A5dD Presumably we're waiting on some other thread to finish up some work before it's able to return to us. Now that Apple has released a fix, I wonder if it's been sufficient time to remove this workaround and save us this potential first paint bottleneck. Hey florian, I know that OS X isn't exactly our most popular platform, but would this be interesting to put under photon-startup?

(For context, I noticed this while debugging ts_paint regressions in bug 1357093)

(In reply to Mike Conley (:mconley) from comment #0) > Hey florian, I know that OS X isn't exactly our most popular platform, but > would this be interesting to put under photon-startup? I would say no, because I don't expect to ever be able to work on this myself within the photon timeframe, but it would be very appreciated if someone fixes it.

Let's just only make this call on OS versions 10.10.0 and 10.10.1 -- the only two OS version affected by the bug.

Comment on attachment 8884176 [details] [diff] [review] fix v1.0 Review of attachment 8884176 [details] [diff] [review]: ----------------------------------------------------------------- Thanks!

Pushed by ryanvm@gmail.com: https://hg.mozilla.org/integration/mozilla-inbound/rev/80e1f0ebd048 Only turn off CGEvent logging on buggy versions of OSX to avoid delays in first paint. r=mstange