Used it awhile ago but crashed.
Uninstalled no problem went back to I.E..
Reinstalled Firefox and tweaked last week now very fast compared with I.E..
Tweak curtsey of about:blank
in the Address bar type
about:config (hit enter)
You will see a whole load of options
Change the following values as stated:
network.http.max-connections = 64
network.http.pipelining = true
network.http.pipelining.maxrequests = 100 or 200 (choose one)
nglayout.initialpaint.delay = 0
network.http.request.max-start-delay = 0
If nglayout.initialpaint.delay doesn't exist, Right click, new integer.
Close Mozilla and start it again.