I thought the scrolling was very smooth, but there was something up with the progress bar, it always bounces back to the initial position when I scrub it.
The logic for the scroller bar at the bottom is fairly complex. We've done many, many hours of usability testing with this and it actually hasn't posed a problem. But I know exactly what you mean. It's actually not bouncing back to the initial position, but it probably looks like that if you have tens of thousands of products displayed there. Try filtering to see the difference.
I was expecting holding down the left and right arrows to have the effect the scrubbing does (Constant scrolling). Currently that doesn't do anything.
Anyhow kudos for the nice interface.