One of my readers, Randall Ehren, was kind enough to provide benchmarks for Xen-virtualized Windows 2003 and XP with and without the optimized PV driver, and also compare to the underlying host. Most of the text below is copied verbatim from his correspondence with me, I just added some clarification in places.
My colleague Ian (last name withheld to save him from the Mac zealots) compiled the postmark code on his beloved Mac and ran it with the same settings I use in general (see older blog posts, just search for postmark).
I’ve been trying out ESET’s NOD32 on my 64-bit 2008 Server box. Before that I’d tried Avast! – which has great detection but noticeably slows down my computer, even when it’s loading pre-cached and pre-checked content (easy test: load Firefox with and without Avast! several times. It’s ALWAYS much slower to load with antivirus on than without. Without Avast! it loads instantly).
I’ve been using Vista x64 for a while now, just so I can make use of all the memory on my machine (an über-thinkpad), and because I like shiny new things and 64-bitness and don’t want to be one-upped by smug Mac users with their feline-named OSes, mock turtlenecks and their newfound 64-bit capabilities. Of course, with the good comes some bad – Vista, while in my opinion a step forward in many ways, does take a step backward when it comes to some areas of performance and sheer resource requirements. A lot of it can be attributed to poorly-written drivers, especially any Aero GUI slowdowns with nVidia cards.