I'm running an i5 imac which chews the heck out of anything it wants to but it keeps tripping up on aperture 3. Very slow to respond. 100% of 8gb RAM used. 60c + Heat build up. 300+% processor power just looking at an image. Although this seems to have stopped when the new update was installed. It seems to be running fast and cool. I think the last patch was a duffer.
I'm scared to install it on the Macbook as that struggles with photoshop a little bit so who knows what it would do if it had to run aperture.
Trust me (I have the same MB) it is painfully slow when using A3 even just to browse pics etc.
I have however purchased 4GB of RAM hoping this will help, so once I receive the RAM I'll be sure to let you know how it performs. Also CS5 with the stock 2GB RAM runs slow as well,
Vel