Video Player - bad performance in build

On OSX I am playing a movie through the Unity Video Player by displaying it on a Render Texture which is applied to a Raw Image component. While the movie is playing, I am loading scenes in the background which at some point get activated.

This is playing very well in the editor, however in a build there are serious performance issues, where the image in the movie is glitching and lagging every x amount of frames. I have attached a screenshot of the profiler view taken from the build.

If I do not have the scenes active in the background, the issue does not occur. Is there something I can do to get the same performance as in the editor?

 

Might be the resolution problem? Because in editor, the resolution might be kept low if is not maximized when play.