I got a second hand HP Spectre x360 (2015) today which came with Ubuntu 20.04 preinstalled and it seemed fine at first but when I connected to the internet I found Firefox to be incredibly slow to load any site I tried to access. Trying to watch a video on youtube took about two minutes to load. Facebook and Gmail both refuse to load properly at all. No matter what site I try, it seems to take at least 30 seconds to load, if it loads at all. This might be the slowest computer I've ever used, and I remember the 90s! I know the internet connection isn't the problem since my other devices work perfectly. I tried to download some other browsers (Chrome, Opera, Vivaldi) to see if Firefox was causing the issue but they all failed to download properly (error message "failed to install file: not supported").

I'm at a loss. I've tried searching for answers online which suggested fiddling with the proxy settings and going to about:config to toggle the "network.dns.disableIPv6" from "false" to "true". and nothing seems to have helped so far. Any ideas please? I like the computer but it's totally unusable for me at this point.