I found this great app yesterday and I wanted to share it with you.
It basically turns your iphone/ipad into a second display, with no latency and great stability.
The app, which is called Duet, must be installed on both pc and iOS device and it works via USB cable (you pay the iOS version only).
It’s very useful if you don’t have enough space for a second monitor and you want to keep a metering plugin always visible. I’m using it with an iPhone, but I think if you have an iPad it would be even better.