What I know, to NLEs
don't like great value GOP because the I-frame are very distance.
I-frames (Intra frames) contains all the information of the image,
P-frames (Predicted frames) and B-frames (Bidirectional predicted
frames) not. Greater GOP value is, smaller file size is (it is
good for streaming and delivery); smaller GOP value is, greater
file size is and more I-frames there are and then it is good for
editing video. With more i-frames cpu consumes less because decode
less information. For video archive would be better GOP=1 (all
i-frames)
Sorry, I guess, you always know that.
However, you have a i7 cpu with a lot of RAM, then your PC should
process your video very good, I think.
Have you tried to use Proxy with scale value to 1/2, just for
testing? If Proxy with "mpeg" you do, the GOP value is 12, then
could be very useful.
(I think, I am writing like Joda Jedi speak) ;-)