If your Firefox installation is generating high memory numbers (you can check it by pressing Ctrl-Alt-Del, going to your Windows Task Manager, clicking on your Processes tab, and checking the "Mem. Usage" and "VM Size" numbers on the firefox.exe line), there's another settings change that might help. Access about:config by typing that exact phrase in the browser Address bar and pressing Enter. In about:config, look for this setting:

browser.cache.memory.enable

Check to make sure its "Value" setting reads "true." Then follow these steps:

1. Right-click anywhere on the about:config window area and choose New and Integer from the pop-up menu.

2. The New Integer Value box will open. Copy this setting name and paste it into the open dialog box:

browser.cache.memory.capacity

3. The Enter Integer Value box will open. The default setting is -1, and it should preserve Firefox's existing mode of operation.

4. Consult this page for more information about what specific setting to add. For RAM sizes between 512BM and 1GB, start with 15000. For RAM sizes between 128MB and 512M, try 5000. Note: If you have less than 128MB of RAM, that's probably the cause of your Firefox issues.