Firefox CPU usage skyrockets unlike non-WebGL web pages

[meglio]

I have been exploring the Immediate Mode GUI concept, and I found a few demos for web applications, including emilk/egui.

One thing I noticed is that the CPU usage by Firefox skyrockets when I play with those demos, unliked with any other pages written with using HTML/CSS/JavaScript.

Q1. Why it happens and is this expected?
Q2. What happens if most of the websites I open in 50+ tabs use the Immediate Mode GUI - will Firefox and OS struggle?

Any input appreciated.

Many thanks,
Anton

[emilk]

Hi!

No, this is quite unexpected! I have no problems in my version of Firefox running on my Mac.

What platform are you on? Laptop/desktop? What graphics card?

Does it still happen if you scale down the browser window?

What does the ms / frame read (left hand side on https://emilk.github.io/egui/)?

[meglio]

• Mac OS Big Sur 11.0.1 (20B50)
• Firefox 83.0 (64-bit)
• MacBook Pro late 2015
• CPU goes quiet ~30 seconds after I switch to another tab.
• ms / frame is always smaller than 5ms
• looks like sizing the window down helps a bit, but it's difficult to measure

Graphics card:

[emilk]

Sounds like a GPU-side problem then. My WebGL skills are not great, and I don't really have the time to investigate this right now. There should theoretically be no problem at all with the GPU rendering, but WebGL is weird and maybe there is some subtlety when using large canvases.

That it is your CPU that spikes seems to indicate that FireFox is rendering on the CPU instead of the GPU, which is weird.

If anyone is good at web tools and diving into why large canvases + WebGL is sometimes so slow, that would be greatly appreciated.

[ghost]

Well, at least confirm, please, that there is no bitcoin miner in your code :)

[meglio]

Re WebGL, I'm not that experienced to dig into it, but for sure desktop games run just fine on this Desktop, like e.g. Witness.

[emilk]

@meglio you can also clone this repo and run cargo run --release -p demo_glium and verify that the exact same Egui demo runs fast when native (as I and epxect it will).

[meglio]

Same issue with the Hobogo game at https://emilk.github.io/hobogo/index.html

[dneumair]

Hi @meglio,
be sure, that you have hardware acceleration in firefox enabled... At least on windows it is possible to turn it off

[emilk]

I've implemented a max-width in egui_web now: https://emilk.github.io/egui - does that help @meglio ?

[emilk]

Thanks to @not-fl3 I now know this is a bug in Firefox: https://twitter.com/fedor_games/status/1342838418343141381 https://bugzilla.mozilla.org/show_bug.cgi?id=1010527#c0

[meglio]

So, let's look at it this way: there is a bug in Firefox that has been there for years, and is still making it impossible to use egui in the browser (one of the major browsers). Kind of being unfortunately ala vendor-locked.

[emilk]

I definitely wouldn’t say it is impossible to use egui in Firefox. It just hurts the FPS and adds cpu usage, but it still works pretty well

[meglio]

When I tested it, it did not work pretty well, unfortunately :( Adding CPU usage that much just makes it not a viable option.