It's ok for me..

I'm not sure if it's that certain sites try to use too many resources (Youtube, FB, etc.) or that I had too many windows open. Mind you, I only had 5 different pages going and the stupid thing kept crashing.

I downloaded FF some months ago when every time I went to youtube - which I love and use a lot - kept giving me a message that I had to upgrade to that or others like Chrome etc so I could continue to view youtube. I chose FF and had loads of problems. Went to their Support area and explained all the problems and got loads of different advice which I followed but still nothing worked and I was just going in circles and getting nowhere, certainly not to youtube. Took me a while to realise all I had to do was upgrade IE to the next level. I'm sure FF works for some, just didn't work for me.

I've laughed Firefox right off now... 

got fed up with all the zillions of toolbars it kept chucking at me...  

Chrome all the way for me!

Thats why I switched to Chrome, am happy so far

I have used Firefox for some time, but haven't had these problems.

Have you looked at Add-ons (from the Tools menu) and checked that you haven't got 2 or more versions of the same add-on enabled. If you have, then things may improve if you disable the older versions. You need to look at Extensions and Plug-ins.

You could also try temporarily disabling an extension or a plug-in to see if that helps. But only try this one at a time so that you can pinpoint the problem. And remember to re-enable it after checking otherwise you lose the use of it.

Firefox has been ok for me but I only use it for this site and a couple of others. The rest is Opera.  I wasn't very  impressed with Chrome when I first used it as it seemed quite slow.  Google hardly have a good reputation for the way they collect personal data, these days.  I also got a bit fed up of Google programs constantly running in the background for no obvious reason or benefit.