Hi,
Native DXVA Hardware Acceleration is in work for MM55, but in MM4.x you should check if you can enable it inside LAV Video Decoder (Icon in Tray).

Also I Suggest using K-Lite codec Pack as it has some Tweaking tools to improve Hardware Acceleration support.

Hi' I've been using MM for a while now as my main video display for my TV, connected to my pc with hdmi.

I've recently bought a 4K TV and when playing 4K videos in MM it lags a little bit, I've checked the system performance and the CPU is at 80-90% while the GPU is like at 10% or something like that (CPU is i5 4Ghz and GPU an Nvidia GTX1070).

I tried the same with VLC media player and the result was about the same, until I checked the hardware accleration option in the VLC settings, then the performance was CPU around 15-20% and GPU 30% or something like that, and no lag whatsoever.
I've checked the MM settings and I could not find this option, is there any plugin for this?

I have MM codec pack extension and FDDshow installed.

Thanks!