1490946 - Modal dialogs in General Preferences show up too slow

Status: RESOLVED WORKSFORME

(Firefox :: Settings UI, defect, P3)

Description

[Mike de Boer [:mikedeboer]]

I noticed a performance problem that most likely has to do with populating the controls with data before the dialog is visible.
I think it'd be good to show an empty dialog with the bottom row buttons at the appropriate size and make its contents visible when it's finished loading data.

I noticed considerable lag using both 'Fonts & Colors' dialogs and the one for 'Language'.

Comment 1

[Jared Wein [:jaws] (please needinfo? me)]

Can you run the profiler to find what is taking so long? We should try to fix the performance issue first.

Comment 2

[Mike Conley (:mconley) (:⚙️)]

This profile shows a 254ms lag between clicking the "Choose" button in the Languages section, and the dialog appearing.

https://perfht.ml/2O4qqBP

Comment 3

[Mike Conley (:mconley) (:⚙️)]

Keeping the needinfo on mikedeboer in case the performance he's seeing is worse - in which case, a profile from him would still be needed.

Comment 4

[Mike Conley (:mconley) (:⚙️)]

Interestingly, we also seem to do a full page paint for some reason just before the dialog comes up.

Comment 5

[Mike de Boer [:mikedeboer]]

Thanks for that, Mike, I don't see worse performance than you were able to measure, I think. What you mentioned in comment 4 sounds like something worth looking into ;-)

Comment 6

[Florian Quèze [:florian]]

I can't reproduce jank anymore when opening the subdialog, but profiling this made me notice the fonts dialog flickers quite a bit. I filed bug 1889445.