Is it un-common for a 10 minute dhcp lease... er yeah.
Would that affect gaming accross a LAN? I dunno. I usually have my dhcp server running as the gateway and Masq box with netradio, and fat downloads going on with different machines and the renewal of 3-4 dhcp leases all at once never makes it hiccup, and its just a puny P133 laptop.
It would make sense to think that there's just too little traffic involved in a lease negotiation to matter in LAN traffic, but I might be wrong.