XP vs Vista overheads

Hopefully not too stupid a question but how does Vista compare to XP
regarding performance overheads. I know Vista is more complex but I was
wondering if it might not also have more efficient code thus negating some of
the increased performance requirments?

So far, after several weeks of testing RC1 I have found it slower than XP HE
in almost every aspect. Although I do have to admit that my XP HE did have
some reg tweaks. Even my internet connection is slower. 174K on XP compared
to 164 on Vista. That's even after disabling the IPv6 that my IP doesn't
support. Page loads as well as graphics are considerably slower with IE7 in
Vista compared to IE7 in XP, and that's with all the same reg tweaks. HP and
Nvidia both do not want to support their customers in Vista, until such times
as the RTM is out. So now it's back to ATI and to hell with Nvidia and as all
of my components are HP, from my $1200 camera to my printer to my tower, it's
time to give this garbage to someone else and purchase a new system from a
manufacturer that sees the sense in following a new OS build and developing
drivers for it. TTFN.
--
There are three types of people in computing, those that can count and those
that can't.