Videos used to run well (⪅ P1W ago), yet don’t anymore, with firefox-148.0.2-1.fc43.x86_64 and firefox-nightly-150.0a1-20260315085700). I’ve checked that hardware decodement is supported in about:support, and:
Although for me, it wasn’t, that didn’t resolve it. Instead, during my diagnosis, I realised that a new profile appeared to resolve this. Consequently, because:
It reproduces, with a synchronised profile, in .x86_64firefox-148.0.2-1.fc43andfirefox-nightly-150.0a1-20260315085700,
It does not reproduce with chromium-146.0.7680.71-1.fc43.x86_64, and
I forgot about -safe-mode. Apologies. That resolves it, [1] although I can’t utilise it forever. I’ll post which extension is the culprit, when I ascertain which is.
In the meantime, does anyone know how to more efficiently diagnose which, so that I needn’t disable all of them, then re-enable each, by one?
I ask because I leave some deliberately disabled during normal usage, so I’ll need to remove them for this process to be feasible, which is an annoyance.
Albeit tangential, if that is of use, insofar as it demonstrates that the browser’s performance is being reduced by something, I wonder whether it could be the cause of:
that seems to indicate that something may be wrong with your firefox profile. Create a new one and see if you can reproduce. Or try disabling extensions…
@marklg, that’s what that argument does, and, thus, how I ascertained the most high-level cause. However, can I more efficiently record video performance, to ascertain which extension is at fault, so that I needn’t brute-force my diagnosis?
IIRC -safe-mode also disables hw acceleration. And as you have not shared the type of GPU in use we can only guess. I would also try different sites if possible. Youtube, for example, seems to be experimenting with detecting ad blockers and then allegedly doing some nasty things to your session.
I hope you did not run firefox-nightly with you main profile. Again, create a, second(?), new firefox profile as a test.
@anotheruser, can that be achieved another way, so that I can confirm that HW acceleration is not at fault? I estimate that an about:config preference exists.
I confirmed with (presumably, H.264 MPEG-4 video, at) Instagram, too.
If you happpen to know of a website that hosts myriad resolutions and codecs of video, specifically for evaluative purposes, that would be helpful.
Yes; it certainly slows the interface. However, video playback was never slowed.
Solely once did I run my Nightly profile in Stable, when explicitly asked to by a Mozilla developer, to diagnose bugzilla.mozilla.org/show_bug.cgi?id=2018809. Otherwise, they are always separate:
