John is completely correct.
As much as I love client/servers, I don't think the biggest advantage of going to a client/server is speed.
V4 improves speed tremendously. A server is not going to give you much more speed.
I would do what John suggests. Switch everything to wired. Make sure everything is GB, which may mean a lot. (GB switch, etc.). And, make sure you have 4GB of RAM on your client running the software. Also, it would help to insure you aren't using the machine running the program.
