ZBrush needs just for sculpting one Core with a high clock-speed to work better.
For rendering however, ZBrush needs so many Cores you can give.
<—The Point is, so many Cores (Multicore Prozessor) you’ve, so more RAM you need.
Because already one Core alone needs a certain of RAM to work well.
Graphiccard ZBrush doesn’t really need.
But you can read all points on the links (especially the first one).
I think for Videoediting and Animation, a computer needs especially
also a powerful GPU/Graphiccard.
But for Sculpting and Rendering is a high clock-speed nesserary.
For Sculpting alone more just one Core will used. For Rendering then your sculpted work, all cores.
But already if you work with one Core, during sculpting, that cores needs its Ram, to work well.
And if you render then your project and the rendering process works then with your multiple cores of your CPU, them all cores needs then for itself their RAM.
Concolusion: So more powerful High-Clock-Speed you have, with more cores together in your Processor, so more better.
Together with more than enough Ram, you are save.
If you want animate or do Videoediting, you’ve also look saddely to a powerful GPU/Graficcard too.
But if you only work with ZBrush and Photoshop, a powerful Processor with high-clock-speed, enough Cores and more than enough RAM will be enough for your workflow.