Firefox Optimization Guide

A collection of Firefox tweaks for optimal performance on any system

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RAM Compatibility Table

RAM Size	Apply These Tweaks?	Notes
32 GB	✅ Full tweaks	High memory system
16 GB	✅ Full tweaks	High memory system
8 GB	⚠️ Slightly modified	Reduce max_total_viewers to 3
4 GB	⚠️ Modified	Reduce max_total_viewers to 1 or 0
2 GB or less	❌ Use different config	See low-memory guide below

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Quick Summary

Category	Action for 16-32GB RAM
AI Features	Fully disabled
RAM Cache	Managed by Firefox (auto)
Disk Cache	Enabled (recommended for SSD/HDD)
Performance	Optimized for high-memory systems

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Disable AI Features

Method 1: One-Click (Firefox 148+)

1. Open Firefox
2. Go to Settings (menu -> Settings)
3. Find AI Controls section
4. Enable "Block AI enhancements"

Method 2: Manual via about:config

1. Type about:config in address bar
2. Accept the warning
3. Search for each preference below and set to false

browser.ml.enable = false browser.ml.chat.enabled = false browser.ml.chat.menu = false browser.ml.chat.page = false browser.ml.chat.page.footerBadge = false browser.ml.chat.page.menuBadge = false browser.ml.linkPreview.enabled = false browser.ml.pageAssist.enabled = false browser.tabs.groups.smart.enabled = false browser.tabs.groups.smart.userEnabled = false extensions.ml.enabled = false browser.search.visualSearch.featureGate = false browser.ml.checkForMemory = false browser.ml.chat.sidebar = false browser.ml.chat.shortcuts = false

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Performance Tweaks (by RAM size)

For 16-32GB RAM

Preference	Value	Description
browser.cache.memory.enable	true	Enable RAM cache
browser.cache.memory.capacity	-1	Let Firefox manage cache size automatically
browser.sessionhistory.max_total_viewers	5	Keep more pages in back/forward cache
dom.ipc.processCount	8	Content processes (adjust to your CPU cores)

For 8GB RAM

Preference	Value	Description
browser.cache.memory.enable	true	Enable RAM cache
browser.cache.memory.capacity	-1	Let Firefox manage cache
browser.sessionhistory.max_total_viewers	3	Reduced for less memory usage
dom.ipc.processCount	6	Fewer content processes

For 4GB RAM

Preference	Value	Description
browser.cache.memory.enable	true	Enable RAM cache
browser.cache.memory.capacity	-1	Let Firefox manage cache
browser.sessionhistory.max_total_viewers	1	Minimal back/forward cache
dom.ipc.processCount	4	Limit content processes

For 2GB RAM or less (Low Memory Mode)

Use the original Reddit tweaks instead:

browser.cache.memory.enable = false browser.cache.memory.capacity = 512000 (512 MB max) browser.cache.disk.enable = false network.prefetch-next = false browser.sessionhistory.max_total_viewers = 0 browser.sessionstore.interval = 600000 browser.sessionhistory.max_entries = 5

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Create New Preference (All RAM sizes)

1. Right-click in about:config -> New -> Boolean
2. Name: config.trim_on_minimize
3. Value: true

Description: Frees memory when you minimize Firefox

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What NOT to change (16-32GB RAM)

These defaults are optimal for your hardware:

Preference	Keep as	Reason
browser.cache.disk.enable	true	Speeds up frequently visited sites
network.prefetch-next	true	Preloads links for smoother navigation
browser.sessionstore.interval	15000	Default 15s is fine
browser.cache.memory.capacity	-1	Don't set manual value

Why not disable disk cache?

With sufficient RAM and an SSD/HDD:

• You have plenty of space
• Disk cache significantly speeds up repeat visits
• Write wear on modern SSDs is negligible

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Recommended Add-ons

Add-on	Purpose
uBlock Origin	Ad blocker, improves speed significantly

Download: https://addons.mozilla.org/firefox/addon/ublock-origin/

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Tips for Different RAM Sizes

16-32GB RAM

• Keep disk cache enabled
• Keep prefetch enabled
• Let Firefox manage memory automatically
• Use native "Unload Tab" (right-click tab) if you keep hundreds of tabs open

8GB RAM

• Close unused tabs regularly
• Use fewer extensions
• Consider an ad blocker to reduce memory usage

4GB RAM

• Use a lightweight Linux distribution if possible
• Avoid opening more than 10-15 tabs
• Disable unnecessary animations and effects in OS

2GB RAM or less

• Consider using a lightweight browser (Pale Moon, Midori, or Nyxt)
• Or upgrade your RAM if possible
• Use text-based browsers (Lynx, w3m) for basic browsing

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Restore Defaults

To reset any preference to default:

1. Go to about:config
2. Find the preference
3. Click the reset arrow (or trash icon) on the right

To reset ALL preferences:

• Use Refresh Firefox (about:support -> "Refresh Firefox")

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Original Sources

• Reddit Post - Firefox Tweaks
• Advanced Firefox Guide by RubenKelevra https://gist.github.com/RubenKelevra/fd66c2f856d703260ecdf0379c4f59db

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Notes

• These tweaks are optimized for 16-32GB RAM systems as primary
• For 8GB or less, use the modified values provided above
• For 2GB or less, use the original low-memory tweaks
• AI disable features work from Firefox 148+ (February 2026)
• Some AI preferences may not exist in older versions

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Troubleshooting

Issue	Solution
Preference not found	Create it manually (New -> Boolean/Integer)
Firefox feels slow (16-32GB)	Reset to defaults or Refresh Firefox
Firefox feels slow (8GB or less)	Reduce max_total_viewers further or close tabs
YouTube playback issues	Set media.ffmpeg.vaapi.enabled back to false

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Quick Reference Card

Your RAM	max_total_viewers	ipc.processCount	disk cache	prefetch
32 GB	5	8	on	on
16 GB	5	8	on	on
8 GB	3	6	on	on
4 GB	1	4	on	on
2 GB	0	2	off	off

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Last updated: March 2026

License: MIT