WMODE - Mac vs. PC and Speed Improvement

I use WMODE set to transparent windowless on my flash movies because it improves the speed of the flash movie when dropped into a browser. however, WMODE set to transparent actually seems to go slower on macs than when WMODE is set to the default setting. i have tried this in safari and IE.

has anyone else encountered this and does anyone know how to get it to work better on macs?

if not, does anyone know a good tutorial that can allow the browser to detect if the user is using a PC or MAC so i can forward MAC users to a different page?