well, a spline object normaly has more polys than a vertex object (but that can depend on the person doing the modeiling so that could be slowing things down a bit, my personal oppion is your going a bit extream on the preview settings, try removing one or two of those, my first sigestion would be anti al.

UV is a system for depecting a 3d object in a 2d way, defining where each poly is in relation to a space on a flat image so if polys overlap on a uv map you'll get all kinds of crazy stuff going on.