[diggan]

I'm unsure if this is actually Firefox fault. I'm running Linux (arch and Ubuntu), Windows and macOS, and Firefox is only slow on macOS, while my macOS machine is the second most powerful machine I have. Running Firefox in a Ubuntu VM on macOS is faster than running it natively on macOS.

[Paul-ish]

Regardless who is technically at fault, the Firefox team is best placed to resolve the issue.

It kind of surprises me that this is an issue at all. I was under the impression a large number of FF devs use Macbooks.

[spiderfarmer]

Yeah, well they know what the problem is but it fails to get a high enough priority to get solved: https://bugzilla.mozilla.org/show_bug.cgi?id=1407536

[pcwalton]

It is highly unlikely that this single issue is responsible for everything reported in this thread.

[vanderZwan]

I find this confusing: there is tons of discussion in the thread, and yet:

> UNCONFIRMED

> Votes: 0 votes

[spiderfarmer]

Yeah plus I find it strange that their telemetry isn’t picking this up.

[jamienicol]

Hi, I'm one of the commenters on that bug.

The discussion is all specific to that page. The biggest issue is that the animations are being driven from Javascript instead of CSS, so there's little we can do to optimize it.

The rest of the discussion is possible heuristics we can implement to optimize how we layerize the page. It would potentially help on this page, but might make things slower elsewhere.

[spiderfarmer]

The problem is not with that page. A simple CSS animation without JS triggers the same issues.

[jamienicol]

Sorry I don't check hackernews for replies frequently.

That bug refers to high cpu load on that page. On that page it is due to the animation being driven from javascript.

If a simple CSS animation causes high cpu usage please file a separate bug with an attached test case.

[Paul-ish]

If it is a JS vs CSS issue, why does it only slow things down on macOS?

[jamienicol]

The site in question on that bug is CPU heavy on all platforms

[BuckRogers]

They do use a lot of Macbooks but Windows users get priority care since they're the meat of their market.

[ComputerGuru]

So you’re proposing this is a macOS gremlin that appears only with Firefox?

Don’t you think it’s more likely there is a bug in macOS-specific Firefox code?

[Avshalom]

Well the thing is it seems to only affect every other mac user even with otherwise identical hardware and os version.

If I had to guess I would chalk it up to a qc issue on some Apple specific chipset that just doesn't get hit by the other browsers code paths and just doesn't get noticed in other less used, less intensive apps.

How to diagnose it or work around it is beyond me.

[diggan]

Well, all cross-platform browsers run slower on macOS than other OSes, at least in my limited testing.

[vondur]

I agree. Firefox seems to run really well on Linux, but seems to just feel slow on MacOS.

[lwansbrough]

Of course it's Firefox's fault. Chrome works fine.

[CyberDildonics]

If other web browsers don't do it, how is it not firefox's fault?