Browser.cache.memory.capacity Jun 2026

On older systems with very limited RAM (e.g., 2GB or less), Firefox’s automatic cache might still be too aggressive. By setting a fixed, lower value (e.g., 32768 = 32 MB), you can force Firefox to use less RAM for caching. The trade-off is potentially slower back/forward navigation.

At its core, browser.cache.memory.capacity is a hidden preference in Firefox's about:config menu. It determines the maximum amount of memory (in kilobytes) that the browser can use to store decoded images, scripts, and other web assets in your system's RAM. Browser.cache.memory.capacity

Any reason not to make more RAM available for browser cache? On older systems with very limited RAM (e

Users can modify browser.cache.memory.capacity to suit their specific needs. The values are measured in kilobytes (KB). At its core, browser

: Sets a fixed limit (e.g., 131,072 KB = 128 MB). Common Use Cases