What could cause stuttering issues?

My computer is not too badly spec wise..

Processor: i7 11700kf (8 core, 16 thread 3.6-5Ghz)

Video: AMD 6700XT 12GB

RAM: 64GB DDR4

O/S: Windows 10 Pro

O/S Hard Drive: m.2 capable of up to 7000mb/s

Hard Drive with my Premiere Project on: m.2 capable of up to 3600mb/s

850 watt power supply and 360mm water cooling setup

I have plenty of hard drive space all over.. you name it.. 

Right now I am editing a roughly 50 minute video. At times when trying to play it back it stutters. Obviously this is not the case in rendering output.

I am running the lastest AMD drivers. I'm eventually going to upgrade RAM to faster stuff.. it's 2666mhz right now. Windows is not running much in the background. Right now I am rendering and it's using 100% of my CPU, but normally there's only a few percentage of CPU usage if that. 

Anything I can do to overcome this issue?