Slow Sessions - Tabs-on-Demand
Armed to the teeth with about:jank, I was testing session restore scenarios that people reported. While at it I came up with a testcase for bug 711193. At first we were going to use telemetry to debate the merits of tabs on demand by default, but I feel my example illustrates responsiveness problems with session-restore well enough. Gavin is looking into this so we can make a decision this week.
On my machine about:jank indicated that most lag was caused by our direct2d accelerated drawing code, bug 721273. Turning off graphics acceleration made things a lot less slow (Options/Advanced/use hardware acceleration) . It would be nice if people experiencing lots of lag in their sessions (on youtube, blogs with high quality backgrounds, etc) could try about:jank. This requires running a very recent nightly.
Install the extension, go to about:jank, browse around, then refresh about:jank. In the case of gfx lag, DrawThebesLayers shows up on top.
Imminent Cycle Collector + GC Improvements
Olli is landing huge cycle collector improvements (half of the patches landed so far), bug 705582, bug 717500. If that doesn’t solve all CC problems by Tuesday, Andrew is standing by with bug 710496 to limit how often CC can run. If we are lucky, incremental JS GC will land before Tuesday too (bug 641025). Landing by Tuesday means that these improvements have a good chance of showing up in Firefox 12. CC + GC are the most well-known causes of pauses in Firefox, so this is very exciting.
Other stuff ****
Telemetry histograms should now survive restarts (so we can do shutdown telemetry, etc), bug 707320.
We are now transitioning from identifying issues to fixing identified issues. It’s exciting to move from speculation as to what sucks to actual results. For more details see meeting notes.