PP,
I have deleted this same question you have made in another of your posts.
Please just start a new topic as you have done here rather than asking the same thing in multiple posts.
It makes it easier to reply to just one topic and easier if it is all in one place.
I am no rendering expert either.
But is seems likely you are using very high settings that you probably don't need.
Try using different render scenes - fast/medium rather than final (or custom).
With the 'final' settings you are probably calculating all sorts of reflections, shadows, grass (even though you don't have any) and many other settings that are just not necessary or not needed with such high calculation values.
Experiment with the different default rendering scenes.
Barry.
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