If GP uses just one core then yes, raw clock speed is better than multiple cores.
However, more RAM now, assuming you can’t update it later, is a wise idea. I’d make sure you have a TB of SSD in that computer so you have plenty of overhead and can record from GP if desired.
I run on a HP Zbook, just a four core single threaded Xeon @ 3.10 GhZ with 32 GB RAM and I’m running a very low buffer size of 128 samples with some pretty heavy VSTs with no issues. If I run into glitches, I increase samples but I like to keep it as low as possible.
In my above setup, I’m typically only using ~15% of my computers CPU although GP reports that I am using 38% of my CPU. I am using about 32% of my memory.
Once GP reports closer to 42%… I start to hear glitches and either need to increase samples or turn off one my VSTs.
I’m using IK’s B3-X which is a resource hog (but sounds so damn good) and a few other fairly heavy VSTs.