The AP V6 requirements are a bit higher, but this in most applies to the user interface. To make it run smooth you can still use a more then 5 year old computer (as long is dual core), but it is more demanding on the side of the graphics card. So a decent graphics card (certainly not high-end) is recommended.
Looking or your configuration everything including video should run smooth. So I suspect codec configuration. If not already installed, I recommend to install K-Lite codec pack basic. Then after that use the Win7dsFilterTweaker to disable windows media foundation. Media Foundation can give a lot of trouble, like stuttering. Currently I have video running smoothly on second screen with a computer of 2007.
I found an article how to use this tool, actually it is a few clicks to disable it.
http://www.addictivetips.com/windows-ti ... ertweaker/After starting the tool press the button "media foundation"
I marked this post a sticky because I suspect that this question will come up more frequently