I do a lot of photo editing on a 13" Macbook Pro. When making photo adjustments I spend a lot of time waiting for the image to re-render. I'm wondering which hardware upgrades will have the greatest impact on adjustment performance and why. (Preferably ranked.)
I use Aperture, but the question should apply just the same to all photo editing software.
Note that I'm taking specifically about performance when making adjustments. I don't care about the time to first load images into the app or the time to export because I can walk away while that is happening. Also, at of the time of this question, all Macs come with flash storage, so recommending an SSD isn't helpful in this situation.