Samsung S5 Screen Mirror to Samsung TV, connects, but hangs/lags every minute

[AC Question]

Hi, Before the Marshmallow upgrade, I could easily screen mirror my videos I took, to my new Samsung TV, via die Screen Mirroring mode. Now, it opens, plays, then after a minute it lags, then comes right, then lags...non-stop. These are not online videos, its ones I took myself, even Videos saved on my Samsung Tablet does the exact same. I have tried the Patch, still the same issue. How do I fix this problem? I don't want chrome cast, I bought this Samsung TV to use this function often. Samsung does not know what to do.