The value you enter is measured in . Here are the most common configurations: 1. Automatic Management (The Default) Firefox/Tweaks - ArchWiki
This setting is not available in the standard Firefox "Settings" menu. To change it, you must use the editor: Type about:config in your address bar and press Enter. Click "Accept the Risk and Continue" if a warning appears. In the search bar, type browser.cache.memory.capacity . Browser.cache.memory.capacity
If the preference doesn't exist, right-click (or use the "+" button), select , and name it browser.cache.memory.capacity . The value you enter is measured in
The preference browser.cache.memory.capacity determines the . Specifically, it sets the maximum amount of RAM (in kilobytes) that Firefox is allowed to use to store cached web content. To change it, you must use the editor:
On low-memory systems, Firefox’s automatic calculation might still be too aggressive. If your system is constantly swapping to disk (the HDD light is always on), you should the memory cache to free up RAM for the OS and other apps.
If you have a high-end machine with 32GB or 64GB of RAM, the automatic cache might be too conservative. You can increase the memory cache to 1048576 KB (1 GB) or more, allowing Firefox to store entire web apps (like Figma, Gmail, or Netflix UI) in hyper-fast RAM.