Very slow playback before editing

I have just installed DaVinci Resolve 17.2.1. and I am new to this software. I can import the MP4 files into Media Pool but when I run the file to do the editing it runs slow and jittering ever 2 seconds. I have checked the file using windows and it runs fine. I have checked the video setting on my Windows 10 pc and my Benq monitor.

The files did come from my Go Pro 8 Black the resolution was 2.7K at 60 fps and were copied direct from the sd card.

Thank you in advance

You need the studio version for hardware decoding. Every third post in this forum is the same question.

Maybe BMD can display a message "Hey GoPro / H265 User. While Resolve is free, it's really useless for anyone not owning a pro camera recording RAW instead of H265."

Doesn't make sense for me from product targeting perspective either. H265 user are low budget consumers, but for those the free version is useless. Why not rather restrict ProRes / DNx support in the free version?