Most users never need to touch this setting because modern Firefox versions (v4.0+) use dynamic cache sizing based on your available system resources. However, manually adjusting it can be beneficial in several scenarios:
: Automatically determines the cache size as a percentage of your physical RAM. 0 : Disables the memory cache entirely. Browser.cache.memory.capacity
While modern browsers are excellent at managing memory on their own, understanding browser.cache.memory.capacity empowers you to optimize your browsing experience to match your specific hardware and privacy needs. Firefox/Tweaks - ArchWiki Most users never need to touch this setting
: Set to false if you want to bypass the slower disk cache entirely and rely only on RAM. Browser.cache.memory.capacity
This setting is found in the ( about:config ). Step-by-Step Instructions