How to get the best possible quality on playback?

We use AgentDVR to do live monitoring, no recoding. We have a beast of a PC and a 4K 65-inch TV, but can't seem to get the best possible quality out of the images. We use a grid, and depending on the number of cameras, the image heavily degrades and seems to get heavily compressed.

-What settings can be changed to get the best quality and sharpness display?
-Is compression applied if each cameras playback is smaller than original stream resolution?

Hardware is not a issue, the PC can take the heat. Even at 36 streams the fan is barely working.