Why is displaying LR thumbnails so processor-intensive?

Question

I'm using 1.4.1 for windows. I appreciate everyone's time who helps me get to the bottom of this.
Why does LR take 100% of my processor resources during folder browsing? What is going on that requires so much power? I'm not yet making any edits to the files at this stage.
My guess is that LR is creating thumbnails and previews. But I set LR to do this at import! LR is set to create 1440 pixel previews, low quality thumbnails, and to keep the preview for 30 days. Upon finishing, I would think this process would be complete (at least for 30 days).
But when I browse to the imported folder, several processor-saturating mystery tasks occur. LR first begins drawing the thumbnails progressively, starting with a totally blurred thumbnail, and after 3 passes, ending with a sharp one. During this, the processor pegs 100%. If the thumbnails were made at import, why does LR display them so slowly compared to other applications using thumbnails?
Second, even after the thumbs are clear, the thumbs show three dots in the top right corner(Loading...). The processor pegs 100%. Does this indicate some kind of preview generation is going on? Didn't I make the previews when I imported though? What is it loading?
Only visible images go through this process. If you scroll to previously unseen location in the folder, LR will start the thumbnail and three dot process again. It WONT do the whole folder in one go. I can't work somewhere else until it is done. I'm chained to the machine waiting for it to finish one screen before moving to the next.
Finally, if I scroll to a part of the folder where this process has previously completed, the thumbs are BLURRY again. Grr. They do render out faster this time though. No three dots.
Can anyone shed some light on what's going on and how to avoid LR tasking the computer so much for these basic tasks?
In contrast, once Adobe Bridge makes a thumbnail, it's made. A thumbnail doesn't disappear only to be redrawn in a three pass blurry-to-sharp processor-saturating progression. What are the benefits to LR's approach? It seems to be very inefficient.
Thanks a ton everybody.

Answer 1

I experience exactly the same problem and that is on quad 3ghz PC with 8GB ram and 10K RPM HDDs. I'm trying now Lightroom 2 Beta and still see this redrawing - takes about 1 second per page. It may be a little bit faster, but it's still annoying - you just can't scroll smoothly through a ton of images. As you said, I don't understand why to re-render when you scroll back to a previous screen that was already rendered once. This annoyance forces me use Lightroom for editing only, and use 3rd party application (AcdSee or Bridge) for browsing/reviewing.