1. Right-click any blank area in the about:config window and choose New > Integer from the pop-up menu.

2. The New Integer Value box will open. Copy and paste this setting name into the open dialog box: browser.cache.memory.capacity

3. In the Enter Integer Value box that opens, enter -1 to preserve Firefox's default operational mode.

4. To customize the setting to your computer's physical memory, consult this MozillaZine page. 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.

Heavy Firefox users should strongly consider upgrading their RAM to at least 1GB.