Profiling contacts app list scroll immediately after load shows that the doRenderTimer() function is taking >30ms. Given that our scrolling frame budget is ~16ms, this is too long. See the profile here at time range 37750 to 37866: http://people.mozilla.org/~bgirard/cleopatra/#report=6d2d991883a5597684e0c09fe7fa88deb5dea891 Its unclear if we can make the work performed by doRenderTimer() more efficient, but we might be able to spread it out more to avoid computation spikes.

This pull request spreads out the contact rendering work during scrolling by adjusting the tag_visibility_monitor parameters. The new parameters result in more frequent updates from the monitor. This comes at a slight overhead cost, but avoids large spikes of modifications at a single time. Overall I think this is probably better than limiting the loop in doRenderTimer() since it avoids creating another layer of code to perform throttling.

Nom koi? because this blocks a blocker.

Triage: Comms team would not block: New perf requirements (see enhancements) but since the contacts performance bug is koi+ by the perf team, letting perf team make the call on this one

Comment on attachment 815554 [details] Pull request at https://github.com/mozilla-b2g/gaia/pull/12778 handing over the review to Francisco as next week I will be on PTO

Comment on attachment 815554 [details] Pull request at https://github.com/mozilla-b2g/gaia/pull/12778 Simple change, tried on the phone and working fine. Thanks Ben!

Thanks! Merged: https://github.com/mozilla-b2g/gaia/commit/01e5ae83a57ac5df4e173edb83c2ad2e2d8dfec0

Uplifted 01e5ae83a57ac5df4e173edb83c2ad2e2d8dfec0 to: v1.2: 46b38f71c65d8bc2a9c5078c6bcca9de79f977a5