[b]Note:[/b] Changing a SubViewportContainer's [member Control.rect_scale] will cause its contents to appear distorted. To change its visual size without causing distortion, adjust the node's margins instead (if it's not already in a container).
Divides the sub-viewport's effective resolution by this value while preserving its scale. This can be used to speed up rendering.
For example, a 1280×720 sub-viewport with [member stretch_shrink] set to [code]2[/code] will be rendered at 640×360 while occupying the same size in the container.
[b]Note:[/b] [member stretch] must be [code]true[/code] for this property to work.