I recently switched to a VISTA 64 machine, Quad, with 6 GB ram. I export 16-bit files from LR. Now the Smart Sharpen routine is horrendously slow - taking upwards of 5 or more minutes to sharpen a 5700x4300px image. If I change the mode down to 8-bits it runs reasonably like it did before (actually it's pretty good on the Quad Core). But what's wrong with the 16-bit file ... is it a bug with smart sharpen on 64 bit architectures or do I have some weird problem with the image size outstripping my processor level 1 or 2 cache (or something like that) causing it to thrash memory. During this period the Task Monitor shows all 4 CPU's at nearly 100%. The problem occurs in both basic and advanced mode.