:not filter is slow in Sizzle

I checked out the latest version of Sizzle and ran the 2 queries below
in slickspeed against the W3C document. I originally began with
body :not(div, span, li) but realized that jQuery 1.2.6 didn't support
it.
body :not(div)
body :not(.example)
They are a lot slower when compared to jQuery 1.2.6.
Might this be related to the fact that :not in Sizzle accepts complex
selectors?
- Kean