Browser.cache.memory.capacity

| Desired Size | Value (KB) | |--------------|------------| | 25 MB | 25600 | | 50 MB | 51200 | | 75 MB | 76800 | | 128 MB | 131072 | | 256 MB | 262144 |

Here is a cheat sheet for different user profiles: Browser.cache.memory.capacity

| User Profile | System RAM | Recommended Value | Rationale | | :--- | :--- | :--- | :--- | | Default / Casual | 8 - 16 GB | -1 (Auto) | Firefox's dynamic algorithm is highly optimized for standard usage patterns. | | Developer / Power User | 32 GB | 256000 (250 MB) | Provides headroom for heavy SPAs and dev tools without starving the OS. | | Legacy Hardware | 2 - 4 GB | 25600 (25 MB) or 0 | Prevents cache from causing swapping. Disable if OS memory pressure is extreme. | | Ramdisk User | 64 GB+ | 0 (Disable) | If you mount the Firefox profile folder to a RAMdisk, disable the internal memory cache to avoid double-caching data in RAM. | | Privacy Focused | Any | 0 (Disable) | Disabling the memory cache ensures that closing the browser leaves zero trace of images or scripts in RAM (though disk cache may remain). | | Desired Size | Value (KB) | |--------------|------------|

The browser.cache.memory.capacity controls the maximum size of the first layer. Here is a cheat sheet for different user

| Value | Meaning | |-------|---------| | -1 | Default (recommended). Firefox automatically manages the cache. | | 0 | Disabled. No memory caching. Drastically slows down session navigation. | | 65536 (64 MB) | Conservative fixed limit. | | 131072 (128 MB) | Moderate fixed limit. | | 262144 (256 MB) | High fixed limit (rarely needed). |

To revert to automatic management, simply set the value back to -1. If you created the preference, you can right-click it and select Reset.