Source: http://www.tomshardware.com/reviews/chrome-27-firefox-21-ope...
When people talk about Firefox being slow, they're not talking about page rendering speeds or JavaScript execution times. They're talking about the longer delays in switching between tabs, in closing tabs, opening a bunch of tabs at once and still having the interface be responsive, and so on. User interface stuff.
Unfortunately, I don't know of any user-interface-responsiveness-speed benchmarks, so it's basically impossible to "prove". But that doesn't mean that people who complain about Firefox being slow are imagining it. The only reason I use Chrome instead of FF on my machine is precisely because the UI is an order of magnitude faster in mundane things -- instantaneous rather than pausing a bit on every little thing.
I still use it because I've become so accustomed to its UI but I switch to Safari on some sites to avoid spinning up the fan.
Chrome on the mac is absolutely dog slow to use, especially after you open up a few tabs. Seriously, why do people say it's fast? I really don't get it. It was fast at one point but now it feels slow, bloated and the tabs crash far more often than either Firefox or Safari. If I only had a penny for every time I see the sad face on tab crashes.
Firefox has no lag whatsoever when switching tabs, and general usage. Maybe people think it's slow because of its dated UI? Maybe they haven't used it at all? Maybe they're still using Firefox 10 or older? Firefox 22 is awesome. People just need to give it an unbiased try.
Safari is the fastest of them all, both in rendering speed and general usage, though it tends to use a LOT of memory.
There exist huge inconsistencies in all of these claims, and it's extremely strange how difficult it is to work out what third variables are involved that are causing such vastly different reports.
This might not be the case one every machine, I don't know, but it's been consistently true for my usage, it just doesn't feel right.
Unlike the new Opera I might add, it provides a really great experience. The fact that you can now install chrome plugins did it for me as I was a vimium addict. I think the move to blink was the right move for them.
https://addons.mozilla.org/en-US/firefox/addon/smoothwheel/?...
Of course, if you're happy with Safari, by all means stick with it.
Performance (aka throughput) measures the total duration of operations, e.g. how long does it take to display a page once it is loaded, how fast a script will be executed, etc. When Chrome was introduced, its performance was much greater than Firefox, largely due to v8. Some other factors involved were add-ons (it used to be really easy to write Firefox add-ons that kill performance, and it used to be impossible in Chrome), or old bloated profiles (which of course didn't exist in Chrome). Now, after lots of hard work, the Mozilla community has managed to make Firefox faster than Chrome. That's what is measured by benchmarks, and that's one point for Firefox. Simultaneously (and this doesn't appear in benchmarks) the Chrome add-on and profile situation have started to show the same weaknesses as Firefox'.
Reactivity (aka snappiness) measures how fast an application appears to be, i.e. the total duration of user-visible pauses, e.g. how long does it take to switch between tabs, or how much one tab eating all CPU affects other tabs. When Chrome was introduced, its reactivity was also much greater than Firefox, largely due to the multi-process architecture. Some other factors involved were add-ons, once again, or old bloated profile, or simply the fact that the Mozilla culture initially didn't take into account this factor. It took some time for the Mozilla community to realize that reactivity was just as important as speed. After lots of hard work, the Mozilla community has managed to make Firefox... well, much better than it used to be. Improvements include off main thread rendering, off main thread disk I/O, asynchronous add-ons, etc. Unfortunately, desktop Firefox does not have multi-process architecture yet. This gives a considerable advantage to Chrome in this domain.
Work is ongoing to bring this multi-process architecture to Firefox desktop. The task is long and difficult and might, unfortunately, kill a number add-ons, but I am confident that the Mozilla community will achieve it.
Incidentally, FirefoxOS has a multi-process architecture already.
Caveat: I'm a Mozillian, and I'm involved in Reactivity work in Firefox.
But yes, both features are rather hardcore. We are working on more user-friendly solutions, too, although I have no idea of the roadmap.
I personally hate Chrome for creating a process per tab. It adds a little bit of security, but it makes harder to manage the processes in a system.
Considering the above, Safari still is (much) faster than Firefox on my machine. I don't care if it can render JS 5% faster - the whole experience is sluggish and slow on my machine. Of course, YMMV.
Just wanted to point it out to you that there are legitimate reasons why people say Firefox is slow.
(UPDATE:) Per <http://support.mozilla.org/en-US/kb/reset-firefox-easily-fix..., it appears 'about:support' is the right place. I suspect this would help, but the problem would recur as soon as I restore my core Add-ons and usual tabs.
In my experience, Firefox gets slower and slower the longer it's been open and with many tabs open. I believe it to be related to GC. Unfortunately, there aren't any hints (like per-tab activity/memory/allocation/timer readouts) as to which tabs are contributing the most to the problem. Sometimes I'll guess the miscreants and closing enough of them helps, but more often things only improve after a restart (essentially unloading all tabs until revisited).
It does seem add-ons are implicated (and perhaps especially Firebug, even if Firebug is not activated in any tab). NoScript may also be implicated; especially with regard to pages that have some but not all script sources enabled.
Read this article to see what it preserves (or "tries to preserve"): http://support.mozilla.org/en-US/kb/reset-firefox-easily-fix...
FWIW, I just tried it and it indeed made things a whole lot faster.
BTW, I didn't find "Reset Firefox" in the about:config page - it was in Help -> Troubleshooting Information.