I'm interested to know which option to choose. I see significant performance improvement using 1024K over 124K or 132K on my system on the kinds of files I usually work with: 100+ pixel layers, vector layers, type layers, masks, effects on 1600 x 1200 px images; and ~14 MB Nikon NEFs, DNGs with only a few adjustment layers and/or masks.
But what about 1028K?
I'm guessing this has something to do with disk block size.
I'm using a 17" MacBook Pro i7 with 8 Gi RAM, and 2 internal 200 Gi OWC Mercury Extreme SSDs set up as a RAID0. The block size on my RAID volume is 32K. It's both my Startup disk (and Application volume), as well as my only Scratch volume.
Thank you!
Also, I'm running OS X 10.6.3 in 64-bit mode with 6Gi allocated to PS.