Nikon d750, z6 II Best specification of computer

I would like to upgrade my computer. What is the best specification of computer components?
Which component is responsible for speeding up the program?
I am currently working on i5 6600k, 32gb ram 3200mhz, gtx 950, m2 samsung 970 evo plus.
It takes 9 hours to modify 1000 files for the program