i have about 35,000 pictures, 4000 songs and 1600 videos, but what i found if i wanted to watch it fairly soon was put the video in it's on directory and have the upnp server scan just that directory and doing a manual refresh, by doing that it would appear a lot quicker
you can give that a try and see if it works, that's what i did on 1.06, haven't put the 1.08 final on it yet ...