Lock Screen vs Login Window - affect on running processes It appears to me that BOTH Apple Menu>Lock Screen AND Fast User Switching Menu>Login Window halt user processes at some point. (AirServer eventually stops working for me)

I would like to know if/why/how user processes are affected in these scenarios.  I've read elsewhere that the Login Window halts processes, and the Lock Screen method shouldn't, but I've personally seen the opposite or inconsistent behavior.

With a better understanding, perhaps a native solution can be found - if one exists, I'd like to know!

I have zero interest in a screensaver, but if it can somehow lock the screen while allowing all background user processes to run, I'm listening.

Yes I have Sleep set to NEVER

I'm familiar with headless windows services automatically starting and running with zero user interaction, not even a need for an initial login.  

I wish to have similar behavior on my Mac mini serving as Plex and Airplay server. 

Unfortunately Plex and AirServer are user processes - so that means I have to log in initially... fine.
I just tested this in my Macbook Air, you can use Shift-Control-Power to lock your screen and it kept the processes running.

If you want to enter lockscreen after this command, you have to setup this option:

and your Energy Saver Settings should look like this: