Are you finding playback slow or editing? If editing, what are you using to edit? What format are the files you're editing in?
I ask these questions because I struggled with editing 4K until I made some changes. I was capturing in 4K H.265 and found editing in Premiere to be incredibly slow and frustrating despite having a 8 core i7, 32GB of memory, fast SSDs and a GTX1080. Then I realised it was the way the H.265 codec works which causes the issues. To render a single frame in H.265, it needs to read and render a few seconds of the video prior to get a full frame. H.264 is similar but less intensive. So for every frame it was rendering hundreds during playback with any effects, adjustements or colour correction turned on.
So I started using CineForm compressed proxy footage in Premiere. Life was good. Only trick with proxy footage in Premiere is that you have to 'turn it on'. Add the proxy button to your playback window and toggle it on.