There's thousands of people out there complaining about the Firefox Memory Bug. Lets get it straight. It's not a bug. It's part of the cache feature. Here are some about:config hacks to make Firefox faster and use less RAM:

Kill the amount of RAM Firefox uses for it's cache feature. Here's how to fix it:
1. type "about:config" (w/o quotes) in the browser.
2. Find browser.sessionhistory.max_total_viewer
2. set it's value to "0"

Increase the Speed in Which Firefox loads pages
1.Type "about:config" (w/o quotes) into the address bar and hit return.
Normally the browser will make one request to a web page at a time. When you enable pipelining it will make several at once, which really speeds up page loading.

2. Alter the entries as follows:
Set "network.http.pipelining" to "true"
Set "network.http.proxy.pipelining" to "true"
Set "network.http.pipelining.maxrequests" to some number like 30.

This means it will make 30 requests at once.

3. Lastly right-click anywhere and select New-> Integer. Name it "nglayout.initialpaint.delay" and set its value to "0".

This value is the amount of time the browser waits before it acts on information it receives. If you're using a broadband connection you'll load pages faster now
More options for your about:config (you might have to create some of these entries by Right Click –> New– > Interger or String

network.dns.disableIPv6: set "false"
"content.notify.backoffcount": set "5"
"plugin.expose_full_path": set "true".
"ui.submenuDelay": set "0" (zero)
Kill RAM usage to 10mb when FF is minimized
This little about:config hack will drop Firefox's RAM usage down to 10 Mb when minimized

1. Open Firefox and go to the Address Bar. Type in about:config and then press Enter.
2. Right Click in the page and select New -> Boolean.
3. In the box that pops up enter config.trim_on_minimize. Press Enter.
4. Now select True and then press Enter.
5. Restart Firefox.

Thats nice, but the real problem is its startup time. Most can live with it, but it'd be nice if it was a bit faster.