netsvcs uses high cpu when opening ICS

I have an Ethernet modem. I connect Internet with it and share my internet
connection with others by using wireless network. Sometimes when I create
Wireless network and others connect it, svchost.exe (netsvcs) uses %40 of cpu
(it is shown in Performance Monitor). When the others disconnect from
wireless network cpu usage becomes normal. How can I solve that. Should I buy
a wireless modem?
(a little note that I've noticed: svcghost.exe isn't shown in Task Manager,
it only shown in Performance Monitor (perfmon))