dj_paige wrote:
if your catalog is on a thumb drive, that may be the speed limitation
You'd be surprised. I just tried it, and could notice no performance degradation. I didn't do any rigorous benchmark testing, but of the things I tried - just as fast, as far as I could tell..
Thumb drive interface is slightly slower but separation of devices makes for improved performance, and it's not (somewhat surprisingly) a critical bottle-neck for Lightroom, for most operations anyway.
dj_paige wrote:
smart previews are stored with the catalog ... I do not think you can put them on a different drive.
You most definitely can put them on a different drive - you just have to access through a link instead of directly on disk.
Rob