By all counts, Pixelperfect should be the clear winner. It requires 6 less HTTP requests, Is almost half the weight (KB) of Novus, and is hosted on the same server.
However..
PixelPerfect has a HTML weight of 17KB, compared to Novus's 3KB. Note that visually at least, they look to have a similar amount of content. The reason for this, and possibly the answer to why Novus is faster, is explained by the fact that GZIP encoding is not enabled on the PixelPerfect Demo.
Andy, would you mind switching on GZIP on PixelPerfect?.. that might serve to both show that it is the fastest commercial J! template ever built, and highlight for everyone here the value of GZIP encoding.
A worthy controlled experiment, if there ever was one.