Best way to send a videostream from UE to another process

I am building a simulator in Airsim which is built upon Unreal Engine. the simulator is rendering 5 cameras in 720p, using a GTX1070 on a windows environment. The framerate is around 30fps while rendering to screen, but when I´m sending it to the decision making engine, I can only get out 4fps. I think the bottleneck is moving data from GPU to CPU memory. I have been looking into Nvidia shadowplay, screenrecording, ue4 render texture to target and computer shader for a continous pipeline stream from GPU to CPU.
Which of these options do you recommend, and are they feasible?

Thanks for your help!