If this article is any indicator of performance across all utilization scenarios, then SP1 for Vista isn't anything to really hold your breath for - as it claims people will only see a 1%-2% perf boost in most cases.

That said, Vista Perf on my box isn't something I'm really worried about. And gaming sites have been showing of late that Vista perf in most games isn't lagging TOOOO far behind XP. In fact in most cases Vista only carries a perf hit of a few frames/second.

So maybe that article's a total red-herring anywho. I think what most people are concerned about with SP1 is how many compatibility problems it addresses. Me, for instance? I'd love to be able to connect to my network attached scanner.