Firefox Settings Worth Changing: Privacy, Performance, and Interface Improvements

Firefox's default settings are reasonable for general users. For anyone who cares about privacy, performance, or how the browser handles specific behaviors, there are specific settings worth changing.

This is not a comprehensive list — it is the settings that most change how the browser feels and behaves.

Privacy settings

Enhanced Tracking Protection (ETP)
Settings → Privacy & Security → Enhanced Tracking Protection

Default: Standard. Consider switching to Strict mode. Strict mode blocks more trackers, including cross-site tracking cookies and fingerprinting scripts. Some sites may break (usually sites that require cross-site cookies for login persistence). The tradeoff is usually worth it.

DNS over HTTPS (DoH)
Settings → Privacy & Security → DNS over HTTPS

Default: Off in many regions. Consider enabling with a privacy-focused resolver like Cloudflare (1.1.1.1) or NextDNS. DoH encrypts your DNS queries, preventing your ISP from seeing which domains you visit.

Sending technical data to Mozilla
Settings → Privacy & Security → Firefox Data Collection and Use

Uncheck "Allow Firefox to send technical and interaction data to Mozilla." Personal preference; the data helps improve Firefox, but if you prefer not to share, it is straightforward to disable.

Performance settings

Hardware acceleration
Settings → General → Performance → Use recommended performance settings

Uncheck this and enable hardware acceleration manually if Firefox feels slow on video-heavy sites. Some graphics drivers conflict with hardware acceleration; if you experience crashes or glitches on video, try disabling it here.

Content process limit
In about:config: dom.ipc.processCount — this controls how many content processes Firefox uses. Modern hardware benefits from 8-16 processes; older machines may work better with fewer.

Interface settings

Compact mode
Settings → General → Density → Compact. Reduces the height of the toolbar and tabs, giving more vertical space to page content. No functional change, just more screen real estate.

Tab scroll
In about:config: browser.tabs.tabMinWidth — set to 0 to prevent tabs from getting cut off at minimum size; Firefox will shrink them and show them all instead of overflowing.

Extensions worth installing alongside these settings

After tightening Firefox's privacy settings, these extensions complete the picture:

uBlock Origin — blocks ads and trackers at the network level. The settings above reduce what trackers can read; uBlock blocks them from loading at all.

NightOwl — dark mode on all websites with auto-scheduling. Install

AI Writing Assistant — if you want grammar checking without sending text to a third party. Install

NightOwl and AI Writing Assistant are two of 11 Firefox extensions I built — see the full series.