Problem we have is the mp4 file created by mavic is a final delivery codec and not efficient to edit with.
The preview in premiere is nothing like playing mp4 in another player, the computer is effectively rendering a new video on the fly.
Most processes in premiere are cpu intensive but a few effects also use GPU.
Also keep the media you are going to be editing on the same drive as premiere is installed. Preferably at least a SATA SSD.
If the preview is stuttering, check what quality setting you have it at and try dropping down to 1/2 or even 1/4.
Its only a preview.
I’ve got an overclocked quad core i7, 32gb RAM, GTX980 6Gb and usually have preview set at 1/2 if I’m using lumetri and a few other effects.
When editing 4k mp4 you just have to accept that preview is never going to be perfectly smooth unless you have a beast of a gaming PC.