MKV 4K REMUX slow or stuttering video

I have tried everything to no avail...the videos continue to stutter.

I am running the video using the latest codec K-Lite Codec Pack (I tried with the beta version, it did not work either).

I have a GeForce GTX 950.

Not all REMUX 4K stutters though, some work just fine which is quite strange.

The complexity of decoding depends an multiple factors, like the video codec and framerate. Right-click on the file in Explorer and choose MediaInfo. Copy that information here, so I can see file details.

One thing you can already try:
MPC-HC options > Playback > Output > Video Renderer > MPC Video Renderer