The speed change happended between beta 10 and 11A. I have no problem with the speed of thumbnail display and start of preview in beta 10. When I try the exact same files, on the same computer, over the same network, on the same NAS, I get slow results with beta 11A. There is a difference between the beta's. My NAS may be the problem, but there must be a code change starting at beta 11a that caused the problem. I am using an Infrant ReadyNAS NV. It is setup using RAID 5. I also tested on Buffalo Terastation, which is using RAID 0 and had no problem with speed. It appears to be compatibility issue with Infrant ReadyNAS NV. I hope there is a fix for PTE to get back to beta 10 performance. Thanks