I've found Firefox performance to be absolutely awful at work on OS X. I have no issues at all with it at home on Linux, and didn't have any issues in my previous job on OS X either. I'm not sure if it's OS X specific, a change in recent versions, this laptop being underpowered, or the nature of the work I do (a lot of video stuff), but anything JS heavy severely slows down or locks up the browser. And if anything, it's gotten worse over the last few months.
I have to use Chrome for anything video related or JS heavy (monitoring/graphing stuff for the most part), but I'd hate to switch to it for everything. There are too many addons that I rely on in Firefox, on top of my general dislike for Chrome's minimalist UI and standard Google privacy concerns.
I've tried turning on the config option for electrolysis, but it breaks some addons, so that's still a no go for me for now.
Any chance you could file bugs, particularly on the JS-related performance issues? I'm looking into some similar things right now, but seemingly JS-centric things seem to have a tendency to actually be from something else. It'd be nice to have something I could solidly blame on JS. If you file a bug with https://bugzilla.mozilla.org/enter_bug.cgi?product=Core&comp... and make it block bug 1299643, I'll see it.
For a while now I've suspected that memory management on OS X is actually terrible. I have no really proof, because I just run everything memory intensive on Linux. At work I have a few Python script that eats a few gigabytes of memory, it reads in data, and basically just loops over it, selects the stuff it needs an generate a few XML file (10 to 20MB worth of XML).
All this takes maybe five minutes on Linux, on Mac OS X it will freeze the OS for long periods of time and take 40 minutes to run. In terms of hardware, the Linux box has less RAM, CPU and slower discs.
Regarding the Javascript stuff: Part of it may be that Chrome is the new Internet Explorer. People develop on and test for Chrome (because everyone uses Chrome, right?). Chrome does have the better Javascript engine, still, I believe that much of the slow Javascript on Firefox (an other browsers) could be avoided if people bothered testing a little more.
Chrome does have the better Javascript engine, still, I believe that much of the slow Javascript on Firefox (an other browsers) could be avoided if people bothered testing a little more.
All major engines are pretty much comparable speed-wise. The biggest difference is probably in memory management (of the HTML & JS engines), which may favor some forms of site/lib structure and architecture over others – that's IMHO where the majority of slowness comes from (for any browser).
I've actually had the opposite experience. I work on Firefox support for a very heavy Angular2 app, and I usually see 2-3x faster reflows on OS X (and Windows) than on Linux, and faster paints too (although I haven't taken exact numbers, since reflows are the bottleneck). It seems that at least the graphics pipeline is much better optimized for OS X/Windows than Linux.
I don't know whether it has accelerated compositing, but in my experience compositing is relatively cheap compared to painting the layers or especially layout. That may be an artifact of the app I work on being poorly composited, however.
It's really hit-or-miss for me too. On my work laptop for example, it would freeze up for multiple seconds with e10s enabled but was fine with it disabled. Then one day everything worked fine. On my home computer FF is just getting slower and slower. I'm not looking for troubleshooting tips here, just mentioning that the experience is very uneven.
I have to use Chrome for anything video related or JS heavy (monitoring/graphing stuff for the most part), but I'd hate to switch to it for everything. There are too many addons that I rely on in Firefox, on top of my general dislike for Chrome's minimalist UI and standard Google privacy concerns.
I've tried turning on the config option for electrolysis, but it breaks some addons, so that's still a no go for me for now.