imac and lightroom 4 problem - how is aperture - thoughts

I run an old 24"iMac 2.93 Core 2 Duo with OSX10.8.2 and LR, but I have 8 gb memory.  No problems.  I also have and use Aperture.  Both programs use about the same amount of resources.  I would think that putting in 8 gb (about $60US) from OWC would improve performance a lot, but I don't think Aperture would run much better on 4gb.

As others have suggested, check your disk permissions using disk utility to see if that might be a problem.

Tom