Browser.cache.memory.capacity

browser.cache.memory.capacity is a powerful lever, but it is just one part of Firefox’s sophisticated caching machinery. It works best when paired with a fast DNS, regular cookie cleaning, and an updated browser.

browser.cache.memory.capacity is a hidden configuration preference in Firefox that determines the maximum amount of RAM (in kilobytes) the browser can use to store decoded images, scripts, and other web assets for immediate retrieval. Unlike disk cache, which persists on your storage drive, this memory cache is volatile and cleared every time you close the browser. mozillaZine Key Functionality Default Behavior (-1): By default, this value is set to Browser.cache.memory.capacity

After 2,500 words of deep analysis, here is the straightforward verdict: browser

Firefox uses a multi-level caching system: Unlike disk cache, which persists on your storage

If you go looking for browser.cache.memory.capacity in the Firefox Configuration Editor ( about:config ), you might not find it. That is because, by default, it is unset. When unset, Firefox uses a dynamic algorithm based on your total system RAM to decide the cache size.

Memory cache is checked before disk cache or network requests.