I've been running the neural one since this morning (for testing)and have yet to have a problem.Yeah I had that problem with Live Wallpapers. Turned them off and went back to basic wallpaper and some of my lag issues resolved. I don't think live wallpapers is all that, with my phone it seem to create more problems than it is worth. Just my opinion.
Some run better than others. It's the nature of the beast : )
Running the one that looks like a pool of water with leaves in it. No lag at all.
Download the 'starfield' one from the Market. Definitely is my favorite.