I've never really suffered this issue too much and it's difficult to tell which things impact performance sometimes. I suspect that you can turn off the preview in the browser tray and that should fix up a lot of the problems right off the bat. For me, when I have more shaders in a folder than I can practically manage on my screen, I then decide which ones to dump to CD Archive and which ones to keep. I don't like too much stuff floating around and I create a LOT of bits and pieces of stuff with Carrara. -Kix

-Kix