This can be a graphics card issue. Adobe is no longer supporting certain cards, so they have a supported card list, I’d check that out. Also, make sure your graphics card driver is up to date, or CUDA driver, but be careful, as some CUDA drivers, from what I’ve experienced, if not the right driver with the right card, with the right OS, with the right version of Premiere, causes issues, so you almost have to find the sweet spot for your computer, but this can also be a lack of enough ram to run your card as hard as you want it to run. Older Macs like my 2009, now have 64GB ram, just to help if needed, with 4-6K playback. Check ram or add more ram. Test your Premiere Pro playback with “GPU-Acceleration” turned ON, and then OFF. This has helped a ton of people out, simply by unchecking this option. I have it tuned off at the moment. Certain edits are fine with or without it turned on. Depends on your computer’s playback and response. The one thing I am thinking though, your graphics card could either be bad, going bad, or the power supply is not getting enough power to the card, to keep it fully powered, causing intermittent hickups or lag in playback. If you are in a huge delemma, turn “GPU-Acceleration” turned OFF, and trouble-shoot your card later, pop it out, and see if it is doing the same thing in another machine. Best of luck on this. My solution last year for me when this happened was to pull out my Mac Nvidia Quadro 4000, and slam in a GTX-770, for now, so far so good.
Tom Laughlin
Producer/Editor
Digital Chop House
Salt Lake City, Utah
http://www.digitalchophouse.com