Some of you know that I've been really worried about the performance we've been seeing of Picasa on Vista. Until now, blttest and ScrollWindow have been 5-10x slower on Vista when compared to XP.
I'm happy to say that Microsoft has turned this around in the latest builds of Vista, and you don't have to write your app in WPF or D3d to get good performance. Legacy GDI apps finally perform well too.
In build 5536 I'm seeing bitblt performance that's within shouting distance of XP, and so even our fullscreen screensavers are performing pretty nicely.