Thanks for the note and welcome to Adobe forums. I'm Kevin, one of the community managers here. I hope the community can help you.
You've explained your problem pretty well, and I've seen this before on my own computer system with certain kinds of footage. That said, it's not easy to solve without more info. It could be multiple issues. Most often, it's related to performance of your hardware and/or difficult media to decode to the screen.
What the community would need to help is finer details about your computer. For example, what is the CPU, GPU, and RAM that are installed? If you have an NVIDIA GPU, include details about the model and driver version. Please also give us details about the CPU: is it an i7, an i9? Can you tell us the generation of the CPU. Is it a 4th, 5th, 7th, or 11th or higher gen CPU?
What footage are you editing with? Is it from a camera, mobile device, a drone? If so, which one. What is the format? Is it H.264, ProRes, etc.
If you are uncertain about these details, we can help. Let us know.