It's you of course! ...... LOL, I'm kidding ..... I wouldn't really know because I haven't had to much experience with ASP. But I would think that ASP may be a bit slower than PHP although ASP is probably improving all the time.
According to a benchmark test http://www.linuxdocs.org/HOWTOs/PHP-HOWTO-13.html:
PHP pumped out about 47 pages/second
Microsoft ASP pumped out about 43 pages/second
Allaire ColdFusion pumped out about 29 pages/second
Sun Java JSP pumped out about 13 pages/second
But who knows when that test took place. I would say overall they're probably really close, but if you did some tweaking/compiling/zend-optimizing to your php scripts then PHP just might come out on top.