Any time you hit a router you are going to pick up a little ping delay. The router has to receive all of the bits in the packet, then compare the destination address to it's routing table (which should be pretty simple for a home router - it's either the local inside net, outside net which includes the upstream gateway). In a home router it also has to swap some IP addresses around (for NAT) and keep track of what goes where, then reassemble the packet, queue it to send with any other outbound traffic, and send it on it's way. It all happens pretty quick, but when you are measuring time in 1/1000's of a second it adds up. Your router is getting it done in 5/1000's of a second, not too bad. There may be a little tuning possibly, but in all likelihood more trouble than it's worth. I don't know that particular router, but various manufacturers have "tweaks" that provide a minimal boost to some traffic at the expense of others. It won't make much difference if you are the only one using the pipe, though.