1660568 - (theme-enable-perf) investigate first-time theme enabling performance in about:welcome and decide what to do

Status: RESOLVED WORKSFORME

(Firefox :: Messaging System, task, P2)

Description

[Dan Mosedale (:dmosedale, :dmose)]

In bug 1643776, we landed a new theme (Alpenglow). Enabling this new theme during the about:welcome flow (and elsewhere, such as from the addons manager theme pane) can (usually?) causes a visual flash in the titlebar. We need to figure out how much of a problem we think this is. On my 2018 Mac, it's somewhat noticable (maybe .25s by eyeball). On a Linux VM I tested, it was fairly noticable, however, it wasn't so noticeable by comparison, since all of the themes rendered slowly enough that one visibly watches them render. On a Windows 7 VM I tested, all three were so slow that it didn't stand out much unless you knew exactly what you were looking forward.

Before multi-stage about:welcome, changing themes wasn't at the front and center of the first run experience; now it is.

So we need to decide how much of a problem we think this is and if we want to invest in it.

I'm guessing the first step here is to try it on a reference machine; perhaps making a video with timings. Punam has a working reference machine; I'm working to resurrect the one i've got.

I'm going to file a separate bug for what we do performance wise, if anything, about the difference between Alpenglow and the other themes in 81.

mconley, lgreco, do either of you know whether there's been theme enabling-performance work done in the past, and if so, how we could find out more and/or leverage those findings?

Comment 1

[Dan Mosedale (:dmosedale, :dmose)]

Note that the biggest part of the performance here is the first time a given theme is enabled after startup. There may also just be a separate painting slowness issues (ie the colors visibly render from top to bottom on some slow VMs, at least).

Comment 2

[Dan Mosedale (:dmosedale, :dmose)]

Much of the analysis in the alpenglow-perf bug is highly relevant to what happens next here.

Jim, what would you propose re if/when we work on theme performance further? If we as a team don't want to drive this, we might be able to find someone else who is interested in it...

Comment 3

[Florian Quèze [:florian]]

I captured a profile of switching the theme from about:welcome a few times on the 2018 reference hardware: https://share.firefox.dev/3jxGyI7

It doesn't seem fast (and I see the white flash) but doesn't seem significantly slower than the rest of the experience on this slow hardware.

Comment 4

[Jim T]

Yes, let's wrap up our work to make sure the performance is at least on par with other experiences in slower environments and see who makes sense to own this type of performance work holistically. Maybe the addons team (cc Jorge)?

Comment 5

[Jorge Villalobos [:jorgev] (he/him)]

Shane, is this something you can look into?

Comment 6

[Shane Caraveo (:mixedpuppy)]

(In reply to Jorge Villalobos [:jorgev] (he/him) from comment #5)

Shane, is this something you can look into?

Not in the near future.

Comment 7

[Shane Caraveo (:mixedpuppy)]

:florian, how does using alpenglow compare to selecing, perhaps dark mode, or some other builtin theme?

Comment 8

[Florian Quèze [:florian]]

(In reply to Shane Caraveo (:mixedpuppy) from comment #7)

:florian, how does using alpenglow compare to selecing, perhaps dark mode, or some other builtin theme?

The profile in comment 3 shows several theme changes (default->alpenglow->dark->light->default->dark->alpenglow). You can see this on the screenshot track. I don't see a significant difference between the themes. The first theme change seems a bit slower than the others.

Comment 9

[:Gijs (he/him)]

We no longer offer theme selection as part of about:welcome, AIUI, so let's close this out?