Will I have any speed increase if I buy an extra SSD drive and put Zbrush program folder there? Should I even try to do it?
Besides the faster load up times, you will find better responsiveness whenever ZB will access the drive on which it is installed.
I have ZB installed on an ssd and it seems to help, but I didn’t really get into sculpting till after I had this setup so I can’t recall a big difference.
In theory it should improve performance, especially when your graphics card won’t help and RAM usage is currently limited to 4GB.
So the bottleneck here probably IS the drive you are using.
I would go for it.
What if I’ll copy Zbrush folder to SSD drive and activate it there? Is it going to use that drive instead of system hdd one?
Not sure about that one, you would have to ask Pixologic support.