MacBook Pro and video editing performance?!

Hi and thanks for reading.

I am using a lot iMovie to make video editing and with HDef clips from a GoPro it takes quite a lot with my MacBook Pro 13'' Early 2011.

Of course this is not a surprise but I am considering to buy a new Mac in the future and wondering how much does the video graphics or the processor speed counts. I need to stay on a MacBook Pro and cannot take a desktop, but I am wondering if on top of a faster processor/SSD/Ram, a video card with dedicated memory like the NVIDIA GeForce GT 750M with 2GB of GDDR5 of the top MacBook Pro Retina 15' can make the difference in video editing or not.

Basically my question is if a video card is important in video editing or if the difference is evident only in video/game simulation play.

Thank you.