Don,
Without knowing all the details, that is a pretty healthy machine; Aperture should be flying. It certainly chugged right along on my Mac Mini with 4 GB RAM, 500 GB 5k RPM drive and a managed Library of 10k images.
Some thoughts, as I have been playing with Aperture a lot since I bought an SSD. (FWIW, the SSD is nice, but it doesn't seem to do much for or against Aperture, the biggest thing is RAM and, to a lesser degree, the GPU.)
An 8 GB MBP with SSD should simply fly.
If you upgraded, You might want to try the "Bergsma Bash." I found this really helped when I migrated from Aperture 2 to 3.
"He suggests that you first make sure to have done all necessary software updates, then delete all files in the following three folders:
Hard Drive/Library/Caches
Hard Drive/System/Library/Caches
Hard Drive/Users/(Your user)/Library/Caches
Also delete this file:
Hard Drive/Users/(Your user)/Library/Preferences/com.apple.aperture.plist
You might want to create a backup first, just in case. But there shouldnât be any danger here, since weâre dealing with cache folders and a âsettingsâ-file for Aperture 3 (youâll have to modify settings again, if youâve changed them in the first place).
Doing the things above and restarting my Mac, solved my Aperture 3 issues."
No guarantees, but I found it helpful and have never had any problems or beachballs with Aperture 3, except on a 2 GB, 2006 MBP.
The other suggestion is to note exactly when Aperture slows down as, at different times, it uses more disk, processor, or RAM. You may find Activity Monitor useful here. Look especially for paging.
For example, scrolling the library is disk/RAM intensive. Brushing, especially with a large file, is processor intensive; you should see all your cores load up.
It is really annoying when Apple software doesn't "just work" but, in the case of Aperture, there is usually a cure. I have a very old, but healthy machine and Aperture runs very nicely.
If all else fails, make an appointment at your local Apple store (should you have one) and get them to help. There are not many Aperture freaks around, but they can read Activity Monitor.
Best wishes.đ