It’s hard to give any specific advice since there are many possible causes for a virtual machine to be slow.
You could start with Task manager in Windows to see what is using the most CPU and memory on the system.
If it is Paratext, you could try saving your current window layout so you can get it back easily and then start closing some windows to see if there is a point where Paratext starts performing better.
There are other tools available, but maybe that’s enough for a start.
John+Wickberg
Paratext support