Changing render settings is not recommented - user
needs this set of settings..
Sure you want the best settings possible, but just try really simple settings and see what happens.
If that works then you might need to compromise somewhere between the simple and complex settings.
It could also be the settings in the surfaces you use.
They don't all need diffusion, luminance, transparency, environment, fog, displacement, grass, etc.
If many of your surfaces have all of these settings and your complex scheme is set to use these options then there will be a LOT more calculating going on when you try to render.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10