How do you want me to say : buy this or that ! somebody that will say that will be stupid and will fool you
You must test using your templates. (I can test your template when I return from holiday after 15/08)
In K4/K5 there are some sounds that are more gready than others
VSL depends of your template, if you use MIR, if MIR is in stereo, 5.1 or 7.1 and needs a balance between a lot of ram, fast cpu and VERY fast disk I/O
Also with Kontakt I will test if it is not better to use Kontakt in standalone !
It's a trial and error !
If I was you I will start to put my Libs on a raid 0 of SSD and see how your system react e.i. see if swapp is still used, I will then reduce pre-load buffer until swap is not any more used, if I still get click and pops I will put more memory
MacBook Pro M3 MAX 128 GB 8TB - 2 x 48" screen --- Logic Pro --- Mir Pro 3D --- Most of the VI libs, a few Synch... libs --- Quite a few Kontakt libs --- CS80 fanatic