I got tired of waiting on the official Froyo and flashed This last night.
[Stock Flash][Odin]Dk17 Extended 11/28/2010 W/ Working Camera Fix. - xda-developers
It's basically a Stock, rooted, dk17 Froyo Rom. 1-click install using Odin, it couldn't get any easier.
I'm not seeing any lag at all. Opened a photo like you described, and it switches to landscape almost instantly when I tilt the phone.
Everything is working great, even Fullscreen Hulu in the Stock browser.
Errr. everything EXCEPT GPS. Have Yet to get a lock. Tried the gpsfix.zip, didn't work. My GPS barely worked on stock D18. May have to try the fix: Flash D18, get a gps lock, flash DK17.