Hello everyone, this here is a really odd problem and not one of the usual "firefox slow, internet bad" → "read the faq" problems as far as I can tell. The problem: When using Firefox (110.0 64-bit Windows 10) I noticed already a while ago that downloads are slow, apparently frozen from time to time, websites took longer to load and looking at speed tests, I got really bad results. Furthermore, Firefox seems to slow down my internet speeds of the whole system, as I can observe in other applications which want to download or upload data. As long as Firefox is running (even if I am just in the default tab and doing nothing in Firefox) it slows the internet speed of the whole system down. So I tried a plethora of things to fix this and I can '''rule out the following''' possible causes with '''high confidence''': * History, Cache, Add-Ons and so on: performed a clean re-install of Firefox, cleared all cache and history data, removed add-ons, reset to default, etc.. * ISP problem: performed repeated speedtests from other devices within the network, everything is fine within my local and wide area network, ISP does not report any problems * Firewall & AV: turning on / off, even uninstalling, no effect observed * Driver problem: driver updated, driver removed, used default Windows Driver, used Troubleshooter etc., nothing helped. * OS issue: Nope. I even performed a clean new installation of Windows today, the problem remains. Furthermore: I ran the speedtests using Microsoft Edge and there are no issues (as long as Firefox is not running.) * HW / System issue: Nopes again. I have used a live Ubuntu-image to cross-check whether the HW might be an issue, but running speedtests using Ubuntu and Firefox worked well. I did not observe similar effects on other machines using Firefox under Windows in my network. So it seems to be a very specific problem within Firefox under Windows 10 on my machine. By the way the machine: HP Pavilion Gaming - 15-dk0200ng CPU: Intel Core i5-9300H RAM: 16 GB DDR4-2666 SDRAM WiFi: Realtek RTL8822BE 802.11ac (via PCIe) (I also have an Ethernet chipset on this system, but since I have tested everything using only WiFi I'll omit the info here.) So is this a bug of Firefox? Or am I missing something? Attached are some screenshots of the disappointing test results using Firefox. (I have similar problems on other sites like speedtest.net or the speedtest of Google). As reference: I've got 500 Mbit/s downstream and 50 Mbit/s upstream. Usually these speeds are achieved from other devices (or other browsers on my system), or are at least within the top 80%. But what I get with Firefox is significantly worse. It's also strange that the speed goes up first, which is fine, but then falls down completely after reaching some point. A few seconds after that it goes up again, but much much slower. Thanks in advance for any help!