After installing Ubuntu 20.04 several months ago I noticed that my computer is running more slowly than before. It takes anywhere from 30 seconds to one minute to launch Chrome browser. Pages load more slowly. Other programs function more slowly. So I ran memtest86 from a restart, and it froze. I have attached a photo of the memtest screen but I don't have the technical expertise to understand the data. Please note the Test at 60% with the hash marks: it has been stuck at 60% for the last ten minutes and nothing else on the screen has changed since then. Please advise as to what I need to do to determine whether I have a problem with memory or other hardware, or if there is a firmware issue, etc. Thank you.
If memtest freezes, you very likely have a hardware problem. It's probably your RAM, but there is no way to be sure.
If you did any overclocking, the first thing to try is to reset that to normal. Similar with RAM timings: If you changed those, reverting them to factory defaults in the BIOS would be worth a try.
If you are sure you did none of that, it's time to replace the RAM. According to the memtest output, you seem to have a single bank of RAM, right? If it's more than one, you could try to remove part of the RAM (make sure the lower RAM banks are filled) and re-check; you might get lucky and find out which of the RAM modules is affected.
But first check if you maybe have an thermal problem: Check the temperature inside the PC case. Open it to see if all fans are spinning. Clean out the dust puppies (very carefully with a vacuum cleaner and if you have it, with compressed air in a can; or with a photo "rocket blower" if you have one).