How to use pool.map effectively?

[wavic]

from concurrent.futures import ProcessPoolExecutor

with ProcessPoolExecutor() as executor:
    results = executor.map(my_func, args=args_list)

multiprocessing.cpu_count() gives the number of the CPU cores. However, if you use all of them it can affect the whole system.
Map method will use all available cores.

I have somewhere a script which downloads in parallel more than 200 web pages and I tested it on 4 core system with a different number of processes. The best time I got was with around 30 processes set. If I found it, I can run the script here again to see what is going on and share it here. This system has 6 cores though.