Thanks for the response. Part of it is probably my computer, which is 6 years old. That is why I am waiting for my new one to arrive, with 4GB ram, running DuoCore processor at 2.4GHz.
Right now I only have 1GB of RAM on a Pentium 4 CPU at 1.9GHz. Running Win XP Pro. The drive on which I have the images is a separate internal drive (separate from the drive that hosts my programs). I am not sure what an "indexed" drive is. The RAW images are from a Nikon D200, and the native resolution of those images (uncompressed NEF) is 3872x2592, @ 240. The thumbnail size is the default PM size. I did not realize there were Cache options for PM (I only recently got the program); what would you recommend for an older system like mine to speed it up a bit?