As I mention in a useless, ranty thread of mine, I’m trying to understand why Firefox’s CPU usage periodically surges over 120% (and more!) when doing even simple tasks in a non-graphic heavy tab.
The first step, I think, is the question I’m asking now: how many tabs do you usually have open in your browser at once? If nothing else, this could get interesting. 
Two.
Usually? Around 50 or so.
Right now? 86
ETA: Wait…Umm, 120% CPU usage? How does that work?
between eight and 20. Right now, three, which is atypical.
I’ve had upwards of 120 open at once while helping my wife with various art projects that needed a lot of photos cut and pasted. Firefox does not always behave itself when that is happening, trust me…even if you have a lot of RAM. And if you have sites with a lot of animated content like JAVA, good luck!
80 to 100 for the past week.
It can be slow occasionally since I’m on a three year old Atom netbook. Before the RAM upgrade it was pretty awful.
Usually: One
Often: Two
Less Often: Three or more
Firefox, Win7Pro
18 at the moment, which is about average.
Right now, 6. Typically… I guess about 15.
I got the CPU usage to hit 14% when I opened 15 tabs to different sites (nothing high intensity, just news sites and blogs mostly). 1,570,000K memory being used.
Anywhere from 1-30, depending if I’m on a youtube whoring streak.
None in Firefox. Tabs are turned off and I’ve removed “New Tab” from the menu bar.
Tabs are the devil’s tracking-cookies spawn.
Usually about 30-40.
Me - half a dozen at most
My wife - upwards of several thousand (on a five year old netbook)
Me - [zipping along with an very light ubuntu installation and minimal crap]
My wife - “why does everything take so bloody long? this thing is crap!”
Me - “how many tabs have you got open?”
My wife - “how can that make any difference?”
Me - [bangs head on table (again)]
One. I sometimes have up to 5 open for up to 30 minutes, but it messes with my mind, man, and I have to close down the ones I don’t absolutely need.
I wish I had the same attitude about putting away my belongings.
I believe that many web pages are full of JavaScript crap, which may chew up your CPU time, especially if you have this happening in multiple tabs (or windows) all at once.
As I’ve written elsewhere, I keep JavaScript disabled on my browser except when I really need it, for things like paying bills on-line (and then, I have ONLY that page open and NOTHING else). BTW, I also have my browser set to delete cookies, cache, and other stuff regularly so I never get a big accumulation.
I do a variety of other things to keep my browser as crippled as possible most of the time. I find that this greatly improves my browsing experience in most cases. Pages load faster, fewer cookies, lots fewer ads, fewer images that I didn’t want to see in the first place, fewer distracting animations, etc.
And this probably protects me from a lot of malware too. I don’t run any virus protection, nor AdBlock or any other Firefox addons. And to the best of my knowledge, I’ve never suffered a malware attack. (It also helps to use Linux.)
Usually around ten when I startup, then I work my way through them and keep open around three or four that I regularly visit for updates.
There are some news aggregate/blog sites where I will open up multiple tabs for each item I want to read, but it’s rare that the total would break fifteen open at any one time.
Right now, I have about 40, across 3 browsers:
Chrome: 7 (most personal stuff like Gmail, BBC News, and the Dope)
Firefox: 25-odd work-related research (I’m on a big programming project at the moment so need to have lots of reference tabs open)
IE: 4-5 work applications that don’t work in anything but IE
9 in Chrome
5 in Firefox
1 in IE (only when required)
Two, occasionally three. Rarely any more.
Using Firefox now but up to a few months ago I was using Chrome. Last few times I have counted I have ended up with 11 each time. Sometimes during a session I will have several more open but the extras get closed as I finish with them.