No, but somehow I get the feeling we're talking about entirely different levels of "slower" here.
You're talking about GPU-accelerating complicated page renders.
I'm talking about things like regularly seeing flashes of unstyled content on page load, which I thought we'd left behind somewhere in the last millennium.
I had a look around for other people with this problem, and all the examples I found were caused by extentions. Ghostery just fixed theirs a few days ago, for example. https://bugzilla.mozilla.org/show_bug.cgi?id=1404468#c36
Based on the differences among different machines I use with Firefox installed, it is certainly possible that extensions are causing a lot of the degradation since Quantum, but I'm not sure assigning blame is interesting or useful here. The fact is that my experience as a Firefox user is now much worse than it was before. The new extension model was supposed to make things faster, more secure, more reliable, but sadly the result seems to have been very much the opposite.
The new extension model makes better extensions possible, but it isn't going to make good extensions appear out of thin air. It's not going to stop a buggy extension from causing FOUCs or slowing down the rendering of a page.
I don't want to make excuses if you're having a bad experience though. But I'm hopeful about the future of Firefox.
The new extension model makes better extensions possible, but it isn't going to make good extensions appear out of thin air. It's not going to stop a buggy extension from causing FOUCs or slowing down the rendering of a page.
OK, but surely it should at least isolate buggy extensions so they can't compromise the browser itself? Wasn't better security and stability in the presence of bad extensions a key selling point of the new extension model? In practice, Firefox was failing to shut down and restart cleanly for me perhaps one time in three since Quantum, having been solid as a rock until that point. (I say "was" because I haven't yet seen this problem since updating to 59 the other day, so it's possible that that particular bug has now been fixed.)
Likewise, if it makes better extensions possible, how come the only observable difference so far seems to be that various things that extensions used to be able to do are no longer possible? It's looking like a classic case of going all-in on a big software rewrite, but finding that a lot of little details have been overlooked and useful functionality has been lost as a result.
The main feature of the new model is that it has less functionality than the old model. Firefox is betting that it can enable close to 100% of the functionality that users actually want via clean APIs instead of opening up literally every internal aspect of the browser to extensions. There will be bugs, but specifying APIs makes them easier to fix.
The advantages are speed, security, ease of installation, ease of development since more thought was put into the APIs, compatibility with Chrome extensions, and better compatibility across platforms since extensions now use less native code. Those benefits are "observable". The downside is that you have to wait for Firefox devs to think though the security, performance, and usability aspects of every bit of functionality an extension dev wants, and then wait for the new or updated extension to exist.
You're talking about GPU-accelerating complicated page renders.
I'm talking about things like regularly seeing flashes of unstyled content on page load, which I thought we'd left behind somewhere in the last millennium.