I had another thought on this idea. How about replacing the image in the customisation screen with a model? Then you could select a logo from a drop-down list like you would with sprays, and drag it onto one of the points on the model to see a live preview. It shouldn't take any more resources, as the models are already cached. I'm gradually getting more attracted to this idea.
Yes, from images I saw going through the OLD empires news on the home page, the models were much nicer to see than the images.
Why would that lag? Thats just the equivalent to adding a few more props on a gmod server, without the complex collison models and physics. If anyone has a computer THAT bad, they really need to get an upgrade for their 10 year old processor and gfx card... The maximum amount of tanks you would normally encounter is about 20, (including tanks on both sides) but even that number doesn't happen very often, (even on money) so there wouldn't be massive amounts of these everywhere.