I guess your whole hardware is too old, also it is only virtualized. Can you reproduce your issues on a I7 or I9 CPU, using a dedicated machine and not a VM? Dedicated machines usely work better for hosting an Avorion server, also we still talk about a game - your Xeon CPU may result in a bad performance. You could try a benchmark and compare to your desktop computer or so...
I just watched your CPU... it is 10 years old, you really should get better hardware. Also I recommand a Desktop CPU, not a server CPU. I have no issues on my server with 20 people online, but you need a high-end server for a really good performance.