Even though not all images will be on screen at once all those images/objects must be rendered, taking up memory .
Gonna have to disagree on that point.
From the Performance Tips section of the manual:
Off-screen objects are not still rendered. Construct 2 does not issue draw calls for objects that do not appear in the window, and the GPU is also smart enough to know not to render any content that appears outside the window - even when a single image is only partially on-screen.
mariogamer Also from the Performance Tips section:
Number of layouts also is unlikely to have any effect other than the download size. The layout size also does not have any direct effect; larger layouts do not use more memory or require more processing, unless you use more objects.