Pause camera / Use last camera image on buffer

Hey Guys, We have two cameras in our game, one for the game, and other for the UI. In some cases, the UI is quite heavy and we want to stop the game camera from updating - but keep rendering the last image, to improve the performance. I've read [this thread](http://answers.unity3d.com/questions/147988/how-to-pause-the-main-camera-.html), but apparently this won't work on mobiles, and we're looking for a solution that works in iOS and Android. Anyone has a clue?