Ron,
imho, nothing from the foundational technologies in IT (CPU , storage size, memory, ..) grow slower than the file size of D-SLRs. The growth in NEF file size from the D1 (1999) to the D800 (2012) was about 10x. Basically, over time, the performance issue rather shrinks than grow
I do have a decent set of fast single socket, dual and even quad socket machines at home, but for photo editing, one of the lower performing machines is more than enough - for what I do.
Usually larger main memory is more useful than a faster CPU.
Unfortunately, quite a few photo editing applications are not leveraging the available parallelism in modern CPUs. For instance Lightroom has its sweetspot with 4 cores. I tested LR on 2 socket machines, but the performance dimishes further as the application can't cope with NUMA architectures at all. LR on a 2 socket 24-core workstation is often slower than on a fast 4-core machine.
As you mentioned notebooks, they are most often limited by thermal design limits, not the max performance a certain CPU architecture could provide. Hence I avoid using notebooks as primary photo editing machines.
To minimize time when selecting keeper images, I use Fastpictureviewer. A properly configured machine is able to display 5-6 D800 RAW photos per second. Basically it is as fast as you can press the keyboard to advance to the next image. Very convenient for the selection process.
My current photo editing machine is a i7-3570K with 32 GB memory and 2x Samsung SSDs for temp space. I don't store files locally, all data is residing in a home server (600k RAW files, 900k JPEGs, approx 7 TB data volume for photos).
I try to minimize my photo editing time, so the workflow is very simple. As example: When returning back from a trip with 5.000 D800 photos (lossless RAW), the selection process to get down to 30-50 keepers and processing in CNX takes about 2-3 hrs in total.
rgds,
Andy