Media Player Fps drops over time

Hey Guys,
I’m making a Interactive VR Movie inside Unreal.
When I started the FPS was perfect, but now is getting slower.
My problem happens shortly after the movie starts slight FPS drops throw the Audio out of sync.

Its Stereoscopic 360 Video mapped to a Sphere (Material Below)
Then using Media player texture I play the film. (Video is Top Down Stereoscopic)
The Videos are H264 3840 x 2448 29.97fps.
For Sound I have 7 Speakers in surround layout.
and I’m using the UVRF playground for VR buttons ect.

Many Thanks if anyone has a solution.

What OS version and UE4 version are you on?