This past week while working offsite I had to use a netbook that was connected to a large screen.
Lightroom was completely unusable in Library mode, so I installed Picasa. It was ridiculously fast in both displaying and editing RAW photos from a Nikon D700. (Who knew that the free Picasa even supported RAW and DNG files?)
We've been constantly hammered with the idea that Lightroom's "modularity" is necessary to ensure that Library mode stays lean and fast. But it's not fast.
I was so impressed with Picasa that, if I could do it all over again, I would probably use that program in place of Lightroom and rely on ACR, Capture One or Capture NX for developing high-value photos.