Actually in general I find the scrolling smoother than IE6.  Opera still rules in this department, IE6/7 will be a littly chunky on some pages with lots of flash animations for example.  Opera is silky smooth on every PC I've tested it on, but IE7 is probably the second closest.  Scrolling speed is definitely not a grip with IE7 for me - it was somewhat in earlier builds, but B3 runs very nicely.

What I did find annoying was that on my GF's machine (XP2500, 512 megs, 6600 GT 128 meg), is that switching between tabs wasn't instant - there was a "redraw" of the screen that was quite noticeable.  Firefox/Opera on her system is instant.

On my system (2 gig A64 3200, 256meg 7600GT) it's also instant, there's no flickering or "repainting" visible when switching tabs.  It's not ram, it can't be processor speed because the difference between out processors isn't as great as the difference in tab switching.  Shouldn't be video cards either as the 2D speed between us is basically indentical, the 7600GT is only faster than the 6600GT in 3D operations.

Anyone else get this?  Her system is very clean and not running a ton of extra crap.