Browser.cache.memory.capacity <2026 Edition>

Essay: "browser.cache.memory.capacity"

Introduction

"browser.cache.memory.capacity" is a configuration preference historically used in some web browsers (notably Mozilla-based browsers) to control the size of the in-memory HTTP cache. It determines the maximum amount of RAM the browser will dedicate to storing cached resources—HTML, CSS, JavaScript, images, and other fetched assets—so they can be served quickly without re-fetching from disk or network.

Modifying this value can have unintended consequences, such as: Browser.cache.memory.capacity

For Power Users with High-End Hardware (32GB+ RAM): Essay: "browser

Per-site memory cache toggle
Users can mark privacy-sensitive sites (banking, email) as "Exclude from memory cache" — those responses go only to disk or not cached at all. This uses the underlying capacity preference but adds site-level exceptions. This uses the underlying capacity preference but adds

The SSD Saver: Some users worry about the constant "wear and tear" of a browser writing small temporary files to an SSD. By disabling the Disk Cache (browser.cache.disk.enable = false) and increasing the Memory Capacity, they force the browser to live entirely in the "volatile" RAM, which clears every time the computer restarts—keeping the SSD pristine and the browsing lightning-fast. Key Settings to Know Preference Recommended Action -1 Let the browser decide based on your system RAM. 0