topic Re: Firefox feels slower overall, especially on GitHub in Discussions

Firefox feels slower overall, especially on GitHub

jehad — Sat, 01 Aug 2026 02:35:05 GMT

I've been using Firefox on Android for a long time, and I'm currently on the latest version. Lately, it feels less responsive than it used to during everyday browsing.

The slowdown is most noticeable on GitHub. Opening repositories, issues, pull requests, or simply moving from one page to another often takes longer than expected. My internet connection is stable, and when I compare the same tasks on Brave or other Chromium-based browsers on the same device, they generally feel smoother and faster.

I've also heard similar feedback from a few people who stopped using Firefox. Their main reason wasn't missing features—it was performance.

I really like Firefox and would prefer to keep using it, so I'm sharing this in case others are seeing the same thing. Is this a known issue, or are there any plans to improve performance on modern websites like GitHub?

Re: Firefox feels slower overall, especially on GitHub

chrcoluk — Sun, 04 Oct 2026 22:11:42 GMT

I have observed the same issue, but for me it started after updating to 157, loading any github page causes a delayed CPU surge 3-5 seconds after page loaded, which is on the main FF process, stalls scrolling etc. githubassets scripts are the culprit, if they are disabled, the CPU surge doesnt happen, but of course the site doesnt function properly either with them disabled.

I agree with you fixing compatibility and performance should always take priority over things like AI features and UI changes.

Re: Firefox feels slower overall, especially on GitHub

zaneselvans — Tue, 06 Oct 2026 08:21:05 GMT

I'm also having constant 3-5 second freezes on GitHub, seemingly no matter what page I'm on, and every 10 seconds or so, which makes writing anything or interacting with the UI very difficult.

Re: Firefox feels slower overall, especially on GitHub

dftf — Tue, 06 Oct 2026 09:47:19 GMT

Odd how many people are suddenly having issues on GitHub, when I've used it at-least twice to report issues since the 157.0 release and haven't noticed any. (Admittedly browsing Issues and filing one won't be the most CPU-intensive thing you could do on there.)

For those who are, can you try:
1. running GitHub in a "Private Window", where by-default no extensions should run; or
2. run Firefox in Troubleshooting Mode (Menu -> Help and Report -> Troubleshoot Mode)

In Troubleshoot Mode, no extensions or custom themes run, and all your settings get ignored. If GitHub works fine there, it's likely an extension causing the issue in your normal mode. If you use ad-blocker, script-blocker, tracker-blocker or extensions that theme pages (e.g. Dark Reader), try turning them off while on GitHub and see if you can identify the one causing the issue.

You can also see if anyone else has reported a GitHub issue here:
https://bugzilla.mozilla.org/buglist.cgi?quicksearch=github

I'm not seeing any reports of GitHub issues in r/Firefox at this time.

Re: Firefox feels slower overall, especially on GitHub

kerny — Tue, 06 Oct 2026 10:03:28 GMT

Same on my side since the update yesterday (v157). It was slow before but there is a huge gap, I can't accept for my daily work on github.

When I switch to another application and come back on an opened PR, the full page is displayed blank and freeze for 5+ seconds. When typing a comment on a PR there are freeze of several seconds where I can't see the char I typed.

If its' not addressed, I will definitely move to another browser.

Re: Firefox feels slower overall, especially on GitHub

dftf — Tue, 06 Oct 2026 10:12:18 GMT

@kerny : if you try GitHub in Menu -> Help and Report -> Troubleshoot Mode... , do you still get the same speed issues then?

If not, an extension you use will likely be causing the issue. Script/ad-blockers (e.g. AdGuard, Ghostery, NoScript, uBO) or page-themers (e.g. Dark Reader) would be the most-likely causes.

Re: Firefox feels slower overall, especially on GitHub

chrcoluk — Wed, 07 Oct 2026 10:52:25 GMT

I think this would be reasonable if the issues didnt suddenly start after a major browser update.

Troubleshooting extensions when the only change in the browser is the build number seems a wild goose chase, but regardless I already have done troubleshooting mode before I posted my first comment and it had no effect.

I can also confirm downgrading to 156 fixed the issue, with the exact same extensions.

However like one of the commenters said, the performance on github on 156 isnt clean, it seems it also spike on that, but the difference is the spike is considerably lower, and there is no block on scrolling etc.

Finally there is a large thread on firefox sub reddit reporting a github issue, and a smaller thread a few days before that.

As kerny said, its not a minor issue, the site becomes very painful to use, its the kind of issue that makes people switch browsers. These type of issues should be the top priority for investigating and fixing. I myself will be uploading a performance trace to try and help get this diagnosed.