Massive CPU usage

Running P4 3.0, 1GB ram, good 512 Graphics card

When running 4 players i get a problem!

When i have 3 streaming and start to navigate with the fourth everything slows down and the cpu usage goes to around 96%

This is the only thing running on the server and i can see the Dvix connected is using the cpu.

All DSM 330's are with the latest firmware, running the latest server.

Any suggestions would be great, in the past i ran 6 with no problems, is it the latest server causing this?

Any help would be great, oh and to add there are no cover art being used, maybe this will make it worse?!

Thanks