Hmmm. The issue has corrected itself at this time but will post this anyway for engineering's info. I went to the console of that server and checked to see if the issue was with Ubuntu or TeamViewer and that's when it corrected itself. Here's hoping it stays that way.
I just installed Ubuntu Server 20.04 and added a xfce GUI. TeamViewer v15.10.5 was extremely slow - two to five second delays when attempting to perform any action with the GUI.
Re: TeamViewer 15.10.5 extremely slow on Ubuntu 20.04
The slow performance of TeamViewer 15 on Ubuntu 20 is confirmed. Going to the console and doing some functions - and then going to TeamViewer on a remote system - will reset (?) TeamViewer so that it performs normally. What causes TeamViewer to stop performing normally and to resume the three to five second delay in responding to an action? I don't know.