i heard firefox is optimized for dial up connection by default.i read in the jan 2008 issue of pc world that you can optimize it for broadband by going to the about:config an tweaking some settings like pipelining and pipelining max request an a few other.my question is does it really work?is it safe?an is anyone out there useing firefox 3 that has done these tweaks to there about:config?
I have had the pipelining changes to the firefox config ever since I can remember - probably before I started using avast - 4 years ago. I have been on FF3 since release day.
As to safe - avast (and my other on demand scanners) have never detected a virus in my system. But if you give it a couple of minutes thought how can the throughput of your connection be related to safety? Either avast scans you connections or it does not … a few more connections is neither here nor there. My connection speed over multiple connections often reaches more than 25Mbps and I am sure that other folks exceed that by far … let us not forget that avast is used worldwide. In parts of Asia 100Mbps connections are commonplace.
Does it work? Well, for years it has been there … so, to be honest, I cannot remember how effective it is. Probably one of those things that shaves a few milliseconds off each access.
Instead of doing the tweaks yourself there is a program called firetune which tunes your firefox you can also return to your previous configuration if the tweak does no good Try Firetune from here
dl1.totalidea.com/files/public/firetune.zip
I tried this and this tuning really works 
To reduce Firefox’s Memory usage, use the following:
http://mysharedfiles.no-ip.org/Browsers/firefox-ultimate-optimizer-11.zip
For tips and tweeks to speedup firefox, check out the following:
http://mysharedfiles.no-ip.org/FirefoxSpeedup/