I've been doing the same and the lag isn't the issue. The real problem is high CPU usage. I can only use the usb monitor for looking at text, anything more (lik

I've been doing the same and the lag isn't the issue. The real problem is high CPU usage. I can only use the usb monitor for looking at text, anything more (like opening a webpage or watching a video in youtube) and the computer slows to a crawl (I'm using the first unibody macbook pro, pre-thunderbolt).