What are the little building tips that you can give us to improve performance and FPS, like building indoors, consume less resources, then building it all open?

Indoors, yes.

Use few signs, don't use signs, don't use lighting.

If you have lumen on, turn it off.

Graphic presets, like usual.

Weather effects, turn them off.

Unfortunately, they're gorgeous, but turn them off.

What else is there?

Basically the hard hitters right now, I would say.