I guess all such things I was asking about should be stated in manuals very long ago. Looks like the project is dead, or at list lack of professional developers and community managers. Lack of everything.
managers are definitely not enough
you shoud have about 2.5 Gb of RAM per core for more effective mining (it's an old information but i don't think that something has changed since)
so for your ryzen you must have 2.5*(8-1)=17.5 Gb of available RAM (or 20 Gb if you will set 8 cores unlike default settings)
if you have less available RAM then divide it on 2.5 and you will get optimal number of cores (but less than 4 doesn't make sense i think)