With the lack of badges and banners, you could try the
Badges and Banners FAQ that I've added on Skins@HWT. That's one possible answer
As for custom WTPs and images, they shouldn't cause any lag. Custom WTPs are never transferred and aren't even considered outside your machine - the other gamers don't care what texture you're using. Lag through processing issues is also unlikely, as the custom WTPs are identical in size and everything to the existing WTPs, and if anything might be a tiny bit faster because they don't have to be extracted from the SGA files (which are basically zipped archives).
Sorry I can't help with anything other than the banner. With network traffic and the possibile variety of other processes on your machine that could interefere, the lag could be due to lots of things.