Firefox about:config — Performance Settings & Common Tweaks
Informationalfirefox
Overview
Guide to Firefox about:config settings for fixing performance issues, adjusting memory usage, controlling content processes, and fixing common browsing problems.
Key Details
- about:config provides access to all Firefox internal configuration preferences
- Changes take effect immediately for most settings (some require restart)
- Incorrect settings can cause instability — use the reset button to restore defaults
- Key performance settings: dom.ipc.processCount, browser.cache.disk.capacity
- Firefox uses Fission (site isolation) which increases memory but improves security
Common Causes
- Firefox using too much memory with many tabs
- Slow rendering due to hardware acceleration issues
- Excessive disk cache slowing down the browser on HDD
- Too many content processes consuming RAM
- Session restore loading too many previous tabs
Steps
- 1Open about:config in the address bar and accept the warning
- 2Limit content processes: dom.ipc.processCount = 4 (default 8, lower = less RAM)
- 3Reduce session history: browser.sessionhistory.max_entries = 25 (default 50)
- 4Disable Pocket: extensions.pocket.enabled = false
- 5Enable strict tracking protection: privacy.trackingprotection.enabled = true
Tags
firefoxabout-configperformancememorysettings
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WarningFrequently Asked Questions
Most changes are safe, but some can cause instability. If something breaks, search for the setting and click Reset to restore the default value.