I am running Photo Mechanic version 4.6.6 and I run Mac OS X 10.6.4 on my Intel-based Mac.
When I open a folder containing approx. 700 RAW images, it takes between 30 sec to 1,5 minute for PM to open the contact sheet.
I have allways had this problem (even in previous versions of PM), but my collegues doesn´t have this problem. Their sheets open instantly.