It appears my hypothesis regarding the disk I/O of LR3 is correct. So I plugged in my external FW800 drive I use as my ‘working’ drive for photo editing and immediately noticed the speed difference when I loaded a library containing photos with lots of spot healing edits. A quick 5 minute hard drive swap and about 3 hours worth of OS and application reinstalls, and data restoration later, I was back up and running with the faster HD on the MBP. So I ordered a Seagate Momentus XT 500GB 7200RPM hard drive from Newegg. It appears that even though the LR3 libraries and source photos are on a separate drive, the LR3 application must be doing a lot of disk I/O on the application volume/drive. Since my iMac had no problems with the same amount of RAM (4 GB) and running the LR3 libraries off the same FW drive, I could only deduce that the system drive was the culprit. I was using the Seagate Momentus 500GB 5400 RPM drive on my MBP and all my LR3 libraries (and referenced photos) are on an external FW800 drive. I finally decided to see if a hard drive upgrade would fix this. My iMac did not suffer the same performance problems as did my MBP.

There were a few updates to LR3 which Adobe claims addressed the issue, but I found those updates didn’t solve my problem. I noticed LR3 would get very lagged when using the spot healing tool. Ever since I upgraded to Adobe Lightroom 3, I’ve found it to be significantly slower than LR2 on my 13″ MacBook Pro.

Lightroom slow on mac