When the client suspends the server will detect a connection loss and suspend the session. All programs and services will stay on the server side as for the programs in the session nothing will be different. The only thing that gets lost is the connection between client and server so you have to reconnect the session on wakeup of the client. You can even reconnect to the session from another client.
Programs in the session might register a slowdown since x2goagent will introduce delays at various places to lower the server load. This can be prevented by adding sleep=0 to /etc/x2go/x2goagent.options.
Uli