You might have clicked on the image and seen just how grainy things are, even after 12 hours of render. Mind you, resize the image and it's fine... photographs are grainy too, so it's not a drama. I guess my question is this: what can you guess might account for the relatively low sample-per-pixel count (82 S/p in 12 hrs) after such a long time rendering? Not the fastest horse in the west:

i3
4 gig RAM
Win 7 64-bit
CPU rendering only - have not tried the GPU version

Oh, and I do notice if I just leave the thing to render and say I want to to anything with the machine after an hour or so, the thing takes forever to respond. Menus drop down eventually, dialogues open in their own sweet time. Why is this? Do you guys get this?

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks