Browser.cache.memory.capacity ((exclusive)) Jun 2026

The advanced configuration preference controls how much system RAM Mozilla Firefox allocates to store web page resources like images, scripts, and stylesheets. By adjusting this value in Firefox's hidden about:config menu, users can directly influence browser performance, cache speeds, and overall system memory consumption.

However, if you search your about:config page today, you might notice this preference is . This often leads to confusion—does it still work? Should you create it manually? The answer is yes, and understanding this preference can dramatically improve your browsing experience, especially if you have plenty of RAM to spare.

Capacity braced himself. Was this the end? Was he being deleted? Browser.cache.memory.capacity

Because this setting is not exposed in the standard Firefox options menu, you must access the advanced configuration editor. Step 1: Access the Configuration Editor Open a new tab in Firefox. Type about:config into the address bar and press .

Modifying about:config settings can affect browser stability. This often leads to confusion—does it still work

: Stores data on your hard drive or SSD. It is persistent but relatively slow to access.

: Set a hard ceiling between 16 MB ( 16384 ) and 64 MB ( 65536 ). Capacity braced himself

However, for the power user with 32 GB of RAM, setting this to 262144 (256 MB) can shave milliseconds off every tab switch. For the developer, setting it to 0 can be a lifesaving debugging tool.

Replace the static numeric pref with a in browser settings (under Performance or Privacy & Security).