Browser.cache.memory.capacity Jun 2026

If the preference exists, double-click it (or click the pencil icon) to edit the value.

In recent versions of Firefox, the transparency of this setting has sparked debate. While the parameter can still be manually added or modified via the Advanced Preferences (about:config) page

"Usage at 95%," the monitor warned. "Renderer lag detected."

The value must be entered in . Use the following breakdown to choose the right setting for your computer: 1. The Ultra-Low RAM / Maximum Savings Profile Browser.cache.memory.capacity

: Very high values (e.g., above 1GB) can lead to memory fragmentation and higher overall browser instability.

RAM is significantly faster than any storage drive, making data retrieval nearly instantaneous.

: This value commands Firefox to auto-detect system specifications and scale memory caching dynamically. On modern machines with ample RAM, it safely scales upwards to ensure snappy page transactions. If the preference exists, double-click it (or click

Depending on your needs, you can set this integer to various values:

sets a limit on the size of any single file allowed into the memory cache to prevent one large file from hogging all allocated space. Mozilla Support recommended manual values for specific RAM capacities like 8GB or 16GB?

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

: Type about:config into your address bar and press Enter. Click the button to "Accept the Risk and Continue."

Here's some information on the browser.cache.memory.capacity parameter:

Disables memory caching entirely. Not recommended unless troubleshooting major leaks. Fixed Size