Firefox Quantum Lands in Beta, Developer Edition

It does actually play into performance, too. The new multiprocess architecture requires that extensions get updated to be compatible with it. It is possible to achieve that in the old extension API, but every single extension author would have to do that, which is just not ever going to happen.

Otherwise, if you install a multiprocess-incompatible extension, Firefox will essentially fall back into single-process whenever that extension does something. So, then a good portion of the extensions on AMO would come with severe, for the user inexplicable performance problems. Mozilla would have just not rolled that out without knowing that the switch to WebExtensions will clean that all up.

Well, and then besides that there's also the points that 1) the old extension API is quite complex, so it's comparatively hard for extension authors to write an extension, especially also qualitatively good extension, 2) the old extension API was really unstable, basically whenever Mozilla changed something about Firefox, some extensions broke, and 3) with the new extension API being based on Chrome's extension API, it becomes often trivial to port Chrome extensions to Firefox, making it much more likely that Firefox will continue to have extensions even if Chrome continues to eat up market share.

Seeing some comments about Firefox vs Chrome on macOS below, here's my experience ...

After several years of using Chrome I've switched to Firefox and I'm not going back. I do occasionally use Chrome, like for Node.js profiling.

In terms of performance, Firefox has been behaving better than Chrome for my usage patterns, using less memory too. Usage patterns matter a lot though. For example Google's own apps (e.g. G Suite) tend to be optimized for Chrome, but I'm not using Google's apps that much.

Stability has been improving, e10s is finally here, we've got multi-processing and it's working. It's not so keen on starting one process per tab as Chrome, but I like that, as memory usage tends to be better.

I've liked the "sandboxing" of Chrome's extensions, having a permissions system that's better than nothing, however I trust Firefox's Add-ons more because Mozilla has a trustworthy review system in place. At the end of the day, when you give permissions to an Add-on for accessing your data across all websites you visit, you can always get screwed with a simple and silent update from that developer and there have been countless of extensions on Chrome's store turned to spyware over night.

Either way, Firefox now has a permissions system in place, they've been introducing it gradually.

In terms of features, I love how natural the Awesome Bar is when trying to go back to a page from history. This is in comparison with Chrome that makes you do more searches on Google. It also has had some great extensions for tab management, some of which are now broken due to the transition, but I'm pretty sure they'll become available again, because hackability is in Firefox's DNA. Consider that Firefox on Android has supported plugins (and ad blockers) from day 1, whereas Chrome still doesn't.

But overall, even if Firefox would be the worst one on the market, I would probably keep using it because it's the only browser whose makers have been looking after my interests as a user, for example being the only major browser that tried opposing DRM or patent encumbered video encoding.

I am averaging around 150 MB per tab here.

I've found that google maps performs worse in firefox and I get random %100 cpu spikes from websites in firefox that I didn't get in chrome. I'm on a mac using firefox 55.

I'm the same but my "logged in" mode browser is Brave. It's chrome + privacy