Dual monitors on MacBook Pro 15' Mid-2012

I have two Apple HD Cinema Displays (23-inch DVI 2005 model) and I want to connect both them to my MacBook Pro 15' using the MiniDisplayport without any lag. I know my mac only supports up to one monitor and I am currently using a USB to DVI to connect the second monitor to make it an extended desktop. I use my mac in boh clamshell and normal mode and the monitor using the USB to DVI is really laggy. I can't watch YouTube videos or do anything graphic intensive without having my second monitor lag. Is there any solution other than the Matrox DualHead2Go Digital Edition that would allow me to connect both my monitors without any lag or issue with graphics.

Note: both my monitors are the older aluminum anti-glare displays, NOT the thunderbolt capable ones.

I'm currently connecting through a MiniDisplay Port to DVI to the first monitor and then a USB to DVI to the second. I am thinking there isn't enough power going to the USB to DVI monitor which makes it lag.

If you have any suggestions or even a possible work around, please let me know 🙂