Running the ro.me benchmark and closing the window in the middle of the animation triggers a 12sec cycle collection on aurora on my MBP: CC(T+191.5) duration: 5ms, suspected: 133, visited: 817 RCed and 8076 GCed, collected: 6 RCed and 0 GCed (6 waiting for GC) ForgetSkippable 23 times before CC, min: 0 ms, max: 3 ms, avg: 0 ms, total: 15 ms, removed: 16184 GC(T+204.7) Total Time: 417.7ms, Compartments Collected: 137, Total Compartments: 137, MMU (20ms): 0%, MMU (50ms): 0%, Reason: PAGE_HIDE, Nonincremental Reason: requested, Allocated: 695MB, +Chunks: 0, -Chunks: 46 Totals: Mark: 387.8ms, Mark Roots: 3.8ms, Mark Other: 372.0ms, Sweep: 28.9ms, Sweep Compartments: 13.1ms, Sweep Object: 10.7ms, Sweep String: 0.4ms, Sweep Script: 0.2ms, Sweep Shape: 1.5ms, Discard Code: 4.3ms, Discard Analysis: 6.7ms, Discard TI: 1.0ms, Sweep Types: 0.6ms, Clear Script Analysis: 0.3ms, Finalize End Callback: 1.5ms, End Callback: 0.8ms CC(T+223.1) duration: 12747ms, suspected: 107, visited: 18221 RCed and 8370386 GCed, collected: 8156 RCed and 8367238 GCed (8375394 waiting for GC) ForgetSkippable 9 times before CC, min: 0 ms, max: 2 ms, avg: 0 ms, total: 6 ms, removed: 1049 GC(T+227.2) Total Time: 128.0ms, Compartments Collected: 142, Total Compartments: 142, MMU (20ms): 0%, MMU (50ms): 0%, Reason: CC_WAITING, Nonincremental Reason: requested, Allocated: 673MB, +Chunks: 0, -Chunks: 2 Totals: Mark: 18.4ms, Mark Roots: 3.9ms, Mark Other: 2.2ms, Sweep: 14.5ms, Sweep Compartments: 4.1ms, Sweep Object: 4.8ms, Sweep Script: 1.3ms, Sweep Shape: 2.0ms, Discard Code: 0.5ms, Discard Analysis: 1.8ms, Sweep Types: 0.3ms, Clear Script Analysis: 0.3ms, Finalize End Callback: 0.8ms, End Callback: 94.9ms

What version of Firefox is this? That's a ton of GCed objects in the graph. Holy moley.

(In reply to Andrew McCreight [:mccr8] from comment #1) > What version of Firefox is this? > 15.0a2 (2012-06-11) > That's a ton of GCed objects in the graph. Holy moley. Yep :)

Bug 754495 should help in this scenario, assuming you don't get unlucky and the compartment merging triggers correctly. Hopefully we can find a more short term way to mitigate this.

I'll see if this improved.

Looks much better now!

Thanks for checking, I forgot to follow up on this!