Firefox Community Forum

Hello,

I am having major issues with Firefox speeds, Mainly upload speeds. On Edge I am getting 400 up & down (no issues at all). However, on Firefox upload speed is 144 Mbps, same on private windows. The only issue is with Firefox. Windows is up to date and Firefox version is 139.0.4 (64-bit)

Attached comparison screenshots for reference.

Below are the steps i performed:

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Firefox Troubleshoot Mode Test: Download: 411.71 Mbps (Full Speed) Upload: 173.03 Mbps (Still Bottlenecked) Extensions Disabled Manually (Normal Firefox): No significant improvement. Hardware Acceleration Toggle (Normal Firefox): No significant improvement.

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New Temporary Firefox Profile Test: Download: ~333 Mbps Upload: ~190 Mbps Problem persists even with a clean profile.

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Temporarily Disable Windows Firewall Test: Resulted in ~349 Mbps Down / ~148 Mbps Up. Firewall re-enabled.

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Could someone let me know how to get this fixed. Creating a new profile should have fixed issued assuming one of the extensions was causing the bottleneck. But even with a new profile its not making any difference.

Suddenly this morning Firefox stopped connecting to any websites. It never gives an error message, it just tries to connect forever. Chrome and Edge can both access the internet without problems. I'm running Windows 11 Pro, and here's what I've tried so far:

Malwarebytes disabled Firewall disabled Turned off all add-ons/extensions Firefox uninstalled and reinstalled Firefox, Windows, Malwarebytes, etc all updated Cache & cookies cleared Refresh Proxy use disabled IPv6 enabled DNS prefetching set to "true" Full malware scan by Malwarebytes Computer restarted (several times)

Any other ideas? Thanks!

my laptop wont let me play Roblox on it it says i need to download the app i click that so it does downloads but it say an error on it and it is not the internet connection. please help i want to play so please write back.

As of February 13, 2025 the front page of the Washington Post website does not load correctly in Firefox 115.20.0esr in Mac OS 10.13.6. The problem persists even in safe mode. Thank you.

I have noticed some minor changes in Google Maps. Unfortunately, they have affected the support of Maps in Firefox (135.0): maps are displayed without any names (towns, streets, objects, etc.). Since this bug is not present in the support of Maps in Edge, I think that Firefox requires a correction. When can we expect a fix?

For weeks now google translate has not been working as it should, when I translate something it usually defaults to translating it to English, but if I change the language to any other than English it still only shows the English translation (or whatever language it got "stuck" on).

I have signed out and in of my google account, have the latest version of Firefox (134.0.2), refreshing the pages doesn't help. I don't have this issue in other browsers.

When I try to sign into eBay, a multi-photo comes up asking me to identify like objects in order to be allowed to enter the program. I believe Firefox is causing this problem. How can I fix the problem?

We are getting errors that css values not defined as if the css file is not loaded from our CDN, which is only happening in Firefox and not other browsers that we support.

We confirmed something changed in Firefox that is triggering this around FF version 132. With the ESR (currently 128.5) and the page is working correctly. When we switched back to latest 133 and the bug is there

In the situations it happens, sometimes our css is NOT being loaded. In others, it is loaded and doesn't work but I see things trying to render before the file shows up in the console network logs. When it works...it is coming up cached. So this feels like a race condition of some type

I'm pretty sure the rule is that css is blocking, because we discussed race conditions when we implemented this, so this might be a Firefox bug? If this is a Firefox bug that isn't in an esr yet, we want to get it filed against firefox and fixed before the next esr.

We even tried a hacky patch on our code's method that is in question, as well as tried putting the expected css font-family style into a <style> tag in our index.html. The patch worked on Windows. It did not work on Mac. Stepping through the code, we see `undefined` / `null`. This definitely implies that the css styles simply have not been applied when the first component asking for the theme is routing through this code.

So again: our Firefox > 132. ESR up to 131 doesn't produce this issue, so something changed in Firefox 132.

If we tried loading our css file in a parent page (just loading, not using) to get it into the mix sooner, it doesn't help. An iframe is still loading faster than its parent frame is loading that css file from the CDN.