3 years ago
3 years ago


(Reporter: rnewman, Unassigned)




Firefox Tracking Flags




(2 attachments)



3 years ago
* Open 11+ tabs with pages, images, etc.
* Open the tabs tray.
* Close the second tab.

You'll see visible animation chop as the tiles reflow, even on a 6S.

A user reported atrocious (fifty-second!) reflow with hundreds of tabs open, so don't stop at 11 if you want clearer symptoms.

This might be just expensive animation, it might be computing a screenshot as a tab scrolls into the visible area, or we might be flushing the set of open tabs at the same time.

Profiling should be enough to figure out what's going on.


3 years ago
Rank: 4
tracking-fxios: ? → +
Flags: needinfo?(sleroux)
Ran the profiler with 28 tabs and wasn't able to notice a significant drop but there was a slight one. Looking at the profiler the culprit looks to be the preserveTabs invocation we make as a result of removing the tab.

I also checked out the scrolling performance of the tab cell and noticed that we are adding/removing subviews every time a cell gets recycled (which is very bad considering we also instantiate a blur view as part of that). See attachments for the profiler outputs.
Flags: needinfo?(sleroux)
Created attachment 8712318 [details]
Screenshot 2016-01-26 14.15.33.png

TabCell.applyStyle slowness
Created attachment 8712320 [details]
Screenshot 2016-01-26 14.17.52.png

preserveTabs slowness

Comment 4

3 years ago
How much of the jank is fixed if we temporarily remove the call to preserveTabs?
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