Hi Lee,
Your ClearTour panos are pretty much smooth for me in Firefox, but even at the auto-rotate speed in IE7 they appear a bit hesitant and jerky. And I agree it doesn't seem to be a CPU issue.
Here's what I find really annoying:
http://www.panoramiques-photo.fr/amiens/
An equivalent sized FPP pano doesn't jerk in IE7 (at least for me).