If this was a recent occurrence, it may have been from the 6.6.5 kernel. There was a WiFi regression in that version that did exactly that, slowed the system to an absolute crawl. I got hit by it on my PC and ended up hosing my whole install (because I panicked and botched things up), but my laptop was fine. I finally got things reinstalled a couple days later when 6.6.6 was released, which fixed the regression anyway.

I had this happen to me recently too, with an EndeavourOS live USB. In my case, it turned out to be due to a faulty flash, reflashing with Rufus fixed it.

I use proxy.griselbrand.com which works really well IMO