Lagging video playback with Macbook Pro

I need help with Premiere Pro lag on my Macbook Pro 2020 16GB

I render clips and playback is okay, then a few minutes later it lags again. If I close and open Premiere Pro again, usually it's smooth for a few minutes and then again it lags. I have tried using Proxies and it does the same (if not even worse). I have 10 GB of storage available on my Mac. 

This is when editing 4K footage. It makes editing so slow.