It's not just Poser 5. Poser 4 and PP also check the network to see if there are other versions running. If you block Poser from the net, it will keep trying repeatedly. This takes some system resources, and slows things down. If you let Poser do its checking, it will check once and stop, freeing up system resources.

Not sure how this works on a computer that is not connected to the net. Perhaps Poser doesn't detect any network if you're not connected?