Two SceneCaptures + RenderTarget on Box Brush = Massive performance issues?

Hey, I’m currently working on Portal 2 in UE4. It’s working good, I have implemented in both (blue and orange portal blueprint) a scene capture 2d for the portal inside (I created a material which handles that inside this blue or orange rim). So if I place an orange and a blue portal and play in editor it will decrease my performance very hard (editor: 60fps, pie: 15fps). What can I change that the sceneCaptures are not that slow? Thanks!

reduce the resolution, dont capture every frame, dont capture when the player isn’t looking at the portal, etc…

Sorry, but how to do that with the “dont captzre” thing=