Media encoder rendering at 10% gpu?

Hi, i am rendering an after effects project, using 3d layers (3d rotations), lights(ambient lights), and cameras (moving cameras)

exporting it to adobe media encorders takes about 2 hours for 00:01:15

i have this specs

i6700k

32gb ddr4

nvidia gtx970

now i have 2 questions

1) is it normal that media encoder is using only 10% of my cpu? does it mean video is rendered by gpu?

2) what do you suggest to speed up process? for example rendering in after effects as animation, than use media encoder to convert, would be faster? and, using just ambient lights, would benefit to deactivate them? aesthetics differences with or without ambient light are very little, having them could be good, but if it cuts rendering times by a lot, i could deactivate them in production didn't seem a so heavy project, had not problems with real time preview

thx a lot for answers, and sorry for not so good english