#2 Nov 06, 2012 00:29
A lot of effort was put to make v5 load CSS files directly from server rather than calling @import. Plus properly configured server and all modern browsers do a good job caching static files.
jQuery and jQueryUI are only loaded when they are needed. You can replace the files with their newer versions too.
You also have full control of what's loaded in your skin, just remove extra require_css calls