1584418 - High CPU usage on Firefox likely due to hidden loading spinners

Status: NEW

(Core :: SVG, enhancement, P3)

Description

[Karl Dubost💡 :karlcow]

Comment from the inital reporter

Just open the site and sit for a few minutes on the first page. Laptop's fan ramps up, CPU load is always at 30-50%. Microsoft Edge do not have this problem. Stable Firefox has the same problem (and webrender makes things only worse)

I created a profile which indeed shows a lot of activity and calls to the same functions
https://perfht.ml/2nHNVoV

There is an animation going on, but still this seems strange it creates that much CPU consumption.

Comment 1

[Mike Conley (:mconley) (:⚙️)]

mstange noticed that this page has off-screen throbbers which might be contributing to the CPU usage.

mstange also noticed that there's an SVG image with an animation on the page.

Hey hiro, this sounds like it's in your wheelhouse - where's a good place for this bug?

Comment 2

[Markus Stange [:mstange]]

Oh dear. The throbbers never go away:

img {
    background: url(/img/loader.svg) no-repeat center;
}

So all visible images have the throbber behind them, which is an SVG with a smil animation inside.

Comment 3

[Hiroyuki Ikezoe (:hiro)]

We can probably add an additional check SMILCompositor::GetFirstFuncToAffectSandwich, presumably we need information that we didn't build any display items for the SVG frame (I have no other ideas right now).