Slow Firefox

[#1]

I have Windows 7 and I have been using Firefox browser for many years but I have noticed recently that it takes about 30seconds for the browser to appear,I just wondered if I should change to Goole Chrome.

[#2]

Try reducing the size of Firefox's cache (Options -> Advanced -> Network). Recent versions of firefox allow the cache to become needlessly large.

[#3]

Since the last few updates I notice that Firefox's Memory (Private Working Set) creeps up and it tends too slow down considerably and it can take a long time to start up.
At present it is using almost 700,000K; I have 3 instances open with around 30 tabs in the first, 16 in another 4 in the last. Occasionally I resort to using the Task manager to close all instances in one go and restarting.
Currently the cache is set to 523MB. I'm unsure as to what other benefits/pitfalls there may be in reducing this. Does anyone know if there is a potential limit of open tabs per instance in FF. I know that if I had more than around 20 in IE8 then it would frequently freeze of crash (rarely use IE9 so haven't tested it).
Is it better, perhaps, to have the tabs spread over more instances or just reduce the number of tabs open in the first place?
I hope the OP doesn't feel I'm hijacking the thread, just thought it might be part of the issue.

[#4]

@Mav - I'm not sure what you mean by "instances" - 3 separate processes using 3 different profiles, or just 3 windows?

[#5]

3 windows each containing the tabs as described.

[#6]

I doubt there's any difference between having 1 window with 100 tabs or 100 windows with 1 tab (other than the ease of moving between 100 tiny tabs).
700MB between 50 open webpages is only about 15MB per page, which doesn't seem that much.

[#7]

I did reduce Firefox's cache and it did the trick it is back to normal I thank you for that