The issues that I found were minor – some strange artifacting appeared on one of my other external monitors, a remnant of a moved Finder window that disappeared when I brought my mouse cursor to the area and high CPU usage, which didn’t otherwise appear to affect performance of apps including Final Cut on my office iMac, but which might affect battery life considerably when used with a notebook. You can adjust frame rate and resolution according to your machine’s performance capabilities, and your battery conservation needs. On the iPad side, you simply purchase and install Duet from the App Store and then open it to get things going, then so long as you’re connected via cable to your Mac and the OS X application is already running, it should find your iPad and automatically add it as another display, just like those you’d connect via Thunderbolt, DisplayPort or HDMI. But once you boot back up, Duet is installed as a menu bar application, and provides a helpful tooltip window at first launch to get you started. This does require a restart, which if you’re like me and almost never do that, plus have thousands of things open, can be a bit annoying. The key to the magic is using a wired connection (via Lightning or 30-pin dock connector) and the mandatory installation of a new display driver on your Mac that will recognize the connected iPad as a monitor. But Duet manages it, and with minimal installation headaches, too.

I was initially highly sceptical of Duet founder Rahul Dewan’s claims regarding his app’s performance – lag free performance, even for games (on recent Macs) with 60fps refresh rates? Sounds like a “go home, you’re drunk” situation.

Duet, a new app from a team that includes ex-Apple display engineering talent, changes all of that with a secondary display experience on an iPad (or even an iPhone) that feels like magic. These things mostly work over Wi-Fi, and work poorly over Wi-Fi at that, with unwatchable video performance, choppy animation and tons of lag, even in the best of circumstances. IPad-as-secondary-display apps have been around almost as long as the iPad, but most who used them once have seldom used them since.

Duest display for mac