rendering clarification

Just want to make sure i have this right.

I'm doing some isometric map stuff so can't use the tilemap object, so using sprites but some will be transparent.

From what i understand transparent object are still rendered with a performance cost, while invisible objects act like objects off screen and won't be rendered (though event logic still takes place). Is this correct?

Thanks.

Pretty much, yup.

It works like that. You can check it by creating at start of layout e.g. 2000 of rotating sprites and see how "visible"/"invisible" and 0 opacity/100 opacity parameters affect CPU.