Video quality problem when creating 360 degree video with Unity

Hi,

I'm creating a 360 degree video on Unity using movie texture. It is basically done by mapping on sphere and the quality of video is very disappointing. Even we've shoot the video with 4K, when we import the optimized quality video into Unity the output came out with lower than HD quality.
Of course we've tried to import the highest quality video but the video is laggy. Would this problem be solved if we use such plugin as AVPRO? Help needed to create high quality 360 degree video without having laggy performance.

Thanks.