I want to make some renders for a pepper's ghost hologram with three sides. So I render with my Object and Cameras linked together in different Scenes. In a different Scene I composite the Scenes so that Suzanne is in the right place with the right size. The render of the composition should have a 1920 x 1080 resolution. BUT the Rendering of the Scenes should happen in a 430 x 430 resolution because that takes WAY less time.
So in the Picture you can hopefully see what I mean.

Somehow I can't get it to work. My Scenes always render in the full resolution of the composition. Takes 1:27 per Frame instead of 00:06 with the lower resolution to render the three scenes.