Most Web designers make liberal use of CSS selectors, but that spec's sibling, descendant and child selectors can cause what designer/developer Shaun Innman calls a "significant, negative impact on page rendering." This is confirmed in tests done by UI Specialist Jon Sykes that are published on his blog.
Fortunately for most designers, the performance impact is only in extreme situations. But it's definitely something to be aware of when writing CSS.
The test was based in part on a comment by Dave Hyatt on an entry from Inman's blog.
Wow. I knew about forcing IRQ priority because I've installed a lot of video cards in my day. A few other things, like going back the the Win2k look, ClearType, and NTFS should be old hat for WinFreaks. But there are some really solid tips over at 
