[2022] Server issues.

This is a typical sign of the server not being able to keep up with the actions of the players, usually an issue that occurs when the hardware isn't powerful enough. You could try to have someone else host the server or using a dedicated machine for it.

High-End unfortunately says nothing in regards to Eco servers, especially with several players and one playing the client on the same computer. As I said, this is the typical behaviour for overload. The other typical behaviour for that is players being disconnected at world ticks.

Eco servers do not use multiple cores well, they profit much more from high frequency than multiple cores (anything beyond two cores after world generation, actually), so depending on CPU model it's very possible for there to be issues with that, yes.

No, there really isn't something you could do. Eco just needs a lot of resources for server hosting. You don't need a second game copy for setting up a dedicated server on it's own machine or a dedicated server. You can also get them at several game server providers like Ping Perfect or G-Portal.