Render Texture Performance

Hello,

I am currently implementing a "portal" like experience where the player can look into another space via a portal.

I am using render textures to show the other space, however there seems to be some lag or jittering when I play the game with the oculus DK2. When the player moves there head around, it seems like the portal is rendering behind the head movements.

Does anyone have insight into why this might be happening?

thanks.