I have installed Ubuntu 18.04 on an AMD Ryzen Threadripper 1950x system. A few applications like Firefox, Thunderbird, and Terminal lag. For example, in both Firefox and Thunderbird, whenever I right click, it takes about 3-4 seconds for the list to appear. Also, in Firefox, whenever I click on an HTML drop-down list to see the context menu, I again have to wait for a few seconds to see the list. In Terminal, right clicking works fin, but whenever I press tab twice to see the list of options or to use autocomplete, it freezes from few seconds.
Here is what I get for
$ free -m
total used free shared buff/cache available Mem: 32085 3061 26536 172 2487 28525 Swap: 2047 0 2047