The only broken-ness I can remember seeing for a long time in Firefox is in those demos and other little projects that pop up here where the developer forgot that browsers other than Chrome exist (or, are using Chrome only features).
I am for all intents and purposes a massive Mozilla fanboy, however I regularly switch to Chromium to use any nontrivial 2D graphics js (e.g. the Python plop profiler).
Not sure why, but Firefox definitely seems to have a weak spot around 2d (SVG?) performance
I submitted three (minor) patches for improving the performance of a couple of filters in Mozilla's SVG code. Those (minor) optimisations should be in this release.
I hope to do a lot more. I too, like you, am a Mozilla fanboy.
Unfortunately, in the last few months, I have a lot of pressure at my day-job (a few sudden departures). Nevertheless, I did contribute when I could spare the time and I urge you to do likewise. If there are enough of us, then there's always someone helping them out. It's a massive project and needs all the hands that kind developers are willing to spare.
If you (or anyone else with time...) want to be a true hero, figure out why font changes for text on canvas is a magnitude or more slower on Firefox than Chrome.
At least on the versions I've tested...
I have an app that places a few hundred text labels on a canvas, and on Chrome I can do that smoothly in a single callback. For firefox I had to use a hack with a queue that is processed a few items at a time with setTimeout() to prevent it from stalling the UI for many seconds... Even so, the experience is still worse on Firefox.
I'm happy to link into this if you point me to a testcase that shows the slowness. If it takes a few tens of seconds so much the better: easier to profile.
I've had some issues with internal sites I use at work that are auto-generated Microsoft stuff. And for a while I couldn't get the new Google Maps to load every time on Firefox. It seems to be have been fixed at some point since it runs fine in Nightly now though.
