I am not responsible for your exports, can’t comment on footage I haven’t seen and you would still need to test the best settings for your particular needs. It should be easy enough to export a few minutes from the start and see if the keyframe settings have any bigger effect on the animation.
You haven’t mentioned anything about your computer. CS6 is quite ancient techwise and newer versions are optimised for better hardware acceleration if your system has support for that eg. Intel Quicksync or Nvidia NVENC for H264 encoding/decoding.