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Firefox Upload Speed Severely Bottlenecked (1/4th of ISP Speed) on Windows - All Troubleshooting Exhausted - Other Browsers/Apps Fine

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Viv
Viv
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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.

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: ===================================== 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. ===================================== New Temporary Firefox Profile Test: Download: ~333 Mbps Upload: ~190 Mbps Problem persists even with a clean profile. ===================================== Temporarily Disable Windows Firewall Test: Resulted in ~349 Mbps Down / ~148 Mbps Up. Firewall re-enabled. ===================================== 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.
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TyDraniu
TyDraniu
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We are working on this under https://bugzilla.mozilla.org/show_bug.cgi?id=1852924

Viv
Viv Frågans ägare
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TyDraniu said
We are working on this under https://bugzilla.mozilla.org/show_bug.cgi?id=1852924

Okay, thank you. Additional information, I tested on Lubuntu on pendrive, On Lubuntu firefox speeds were 100% accurate and there was capping or throttling. Only issue is while on Windows (in my case Windows 10)

Ändrad av Viv

TyDraniu
TyDraniu
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I'm not sure if they use http3 on Lubuntu. There's no issues with http2. Check network.http.http3.enable in about:config.