Can't Watch Films And Play Game At Same Time

I run dual monitors and When I was rocking windows 8.1 I could game and watch movies at the same time with with no problems.

Now I have upgraded to 10, every time I try and watch something the picture lags but the not the sound when I'm on a game. But if I select the tab running the film it runs fine even with the game running in the background. But as soon a select the game it go's back to being crap and stutters/lags.

This happens while using VLC, windows media player and streaming online with things like YouTube, Netflix and everything you could think of for streaming films.

I've done many scans to check for a virus and nothing came up.

Probably not the cause but the game I play is called warframe.