10 Firefox Tweaks That Actually Make a Difference

Introduction

There are plenty of Firefox optimisation articles out there, with lists of dozens or even hundreds of about:config settings. I used to follow them blindly, but over time I realised that most of those tweaks made no noticeable difference – and some even caused compatibility issues. Now, every time I install Firefox, I only stick with a handful of settings. They won't transform the browser, but they genuinely improve the everyday experience.

I used to love digging into about:config and trying every "hidden optimisation" I came across. In the end, very few of them actually stuck. More often than not, a smoother, more stable browsing experience matters more than chasing benchmark scores. This article is about the 10 tweaks I've kept after years of using Firefox.

1. Enable HTTPS‑Only Mode

This setting forces all connections to use encrypted HTTPS. By default, Firefox tries HTTPS first but falls back to HTTP if a site doesn't support it. HTTPS‑Only Mode is stricter – if a site doesn't support HTTPS, it blocks the connection and shows a warning. This is especially useful on public Wi‑Fi, because HTTP traffic is transmitted in plain text and anyone on the same network can intercept your data. You can find it in Settings → Privacy & Security → HTTPS‑Only Mode, and choose "Enable HTTPS‑Only Mode in all windows".

2. Enable DNS over HTTPS

Traditional DNS queries are also sent in plain text, so your ISP can see which websites you're visiting. DNS over HTTPS (DoH) encrypts these queries, preventing third parties from easily snooping on your browsing history. You'll find this option in Settings → General → Network Settings – check "Enable DNS over HTTPS". The default provider is Cloudflare, but you can also use NextDNS or other custom providers. If you care about privacy, this is worth turning on. However, if you're in China, it's advisable to use a local DNS provider or test connectivity first, as DoH may sometimes cause resolution issues depending on your network environment.

3. Make Sure Total Cookie Protection Is Enabled

This is part of Firefox's Enhanced Tracking Protection and is enabled by default in Standard mode. It works by giving each website its own separate "cookie jar" – cookies from site A can't be accessed by site B. Previously, third‑party trackers could follow you across different sites using cookies; Total Cookie Protection blocks that completely. If it's been disabled for some reason, you can check about:config and search for network.cookie.cookieBehavior – make sure its value is 5 (the default in Standard mode).

4. Enable the Rust Ad‑Blocking Engine (Experimental)

Starting with Firefox 149, the browser quietly added a Rust‑based ad‑blocking engine, the same one used in Brave. Its main advantage is performance – Rust is known for memory safety and efficiency, which makes it great at handling large numbers of filter rules. Currently, it's disabled by default and has no user interface. To enable it, go to about:config, search for privacy.trackingprotection.content.protection.enabled, and double‑click to set it to true. If you already use uBlock Origin, this engine can complement it and make page filtering feel even smoother.

5. Disable Telemetry and Data Collection

By default, Firefox collects technical and interaction data to help Mozilla improve the browser. This data is anonymous and doesn't affect ordinary users. But if you, like me, prefer not to have software silently uploading data in the background, you can turn it off. Go to Settings → Privacy & Security, scroll down to "Firefox Data Collection and Use", and uncheck "Allow Firefox to send technical and interaction data to Mozilla".

6. Disable Pocket (If You Don't Use It)

Pocket is Firefox's built‑in "read‑it‑later" feature, with entries in the address bar and the new tab page. If you never use it, it only clutters the interface. I prefer a clean browser, so I always turn it off. In about:config, search for extensions.pocket.enabled and double‑click to set it to false. After that, the Pocket button in the address bar disappears, and the new tab page stops recommending Pocket articles.

7. Tweak Tab Behavior

There are a few tab‑related settings I tweak out of habit. In about:config, search for browser.ctrlTab.sortByRecentlyUsed – set it to true, and Ctrl+Tab will cycle through tabs in most‑recently‑used order rather than left‑to‑right. Another one is browser.tabs.loadInBackground, which is true by default, meaning new tabs load in the background. If you prefer that content loads when you switch to the tab, keep the default; if you'd rather save resources by loading only when you switch, set it to false.

8. Install uBlock Origin

This isn't a built‑in Firefox setting, but it's the only extension I always install. uBlock Origin is one of the most powerful ad blockers available, with active rule maintenance and great compatibility. Once installed, pages load cleaner and many unnecessary network requests are blocked. If you only install one Firefox extension, this is the one I'd recommend.

9. Check That Hardware Acceleration Is Enabled

Hardware acceleration lets Firefox use your GPU to handle video, animations, and page rendering, which usually improves browsing smoothness. In Settings → Performance, you'll find "Use recommended performance settings" – it's checked by default, and below it, "Use hardware acceleration when available" is automatically enabled. In most cases, leaving it as is works best. If you have an older graphics card or encounter display issues after enabling it, you can try turning it off.

10. Customise Your Search Engines

Firefox's default search engine list includes a few I rarely use. I go to Settings → Search, remove the ones I don't need, and reorder the rest to my preference. If you use DuckDuckGo, Startpage, or Kagi, you can add them as well. This is a small change, but it makes address‑bar searches more convenient without having to switch engines every time.

Tweaks I Don't Enable

Many articles suggest changing dozens of about:config parameters – tweaking cache sizes, disabling animations, modifying network thread counts, or turning off security features to "speed things up". I've tried most of them and ended up reverting to defaults. The reasons are simple: the gains are minimal, they often break after updates, and some can even affect stability. For instance, adjusting network thread counts might slightly improve load times in some network conditions, but in others it can actually slow things down. Disabling animations does make the interface feel snappier, but at the cost of a more rigid browsing experience. To me, those trade‑offs aren't worth it.

There's also a category of tweaks aimed at reducing memory usage – like adjusting browser.sessionhistory.max_entries. They might save a bit of memory, but they also degrade the browsing experience – for example, the back button may lose some history. I'd rather let Firefox manage its own memory than fiddle with such details.

Over time, I've come to realise that browser performance is a holistic thing – changing a few random parameters rarely makes a significant difference. What truly affects daily use are the basics: privacy protection, ad blocking, and network encryption – not the obscure "hidden tricks" buried deep in about:config. Of course, this is just my personal experience; if you enjoy experimenting, feel free to try them out.

Further Reading and Alternatives

If you're interested in more Firefox customisation, these are also worth checking out: Betterfox – a curated collection of Firefox optimisations; Arkenfox user.js – a privacy‑focused Firefox configuration for advanced users; Firefox Multi‑Account Containers – an official extension for isolating browsing sessions; Sidebery – a sidebar tab management extension; and Auto Tab Discard – which automatically frees memory from background tabs.

Final Thoughts

There's no one‑size‑fits‑all set of browser settings – everyone's habits are different. These 10 tweaks are simply the ones I've kept after years of using Firefox, based on real‑world experience rather than benchmark scores. If you're new to Firefox, start with these and adjust as you go. After all, a browser is something you use every day – and feeling comfortable with it matters more than anything else.