MacBook Pro 14 M1 Max lagging when editing 4K videos in iMovie
I have a hi-spec M1 Max 14" MacBook Pro purchased in December 2022. I have recently been putting together a movie with some 4k footage filmed with a GoPro. When importing the footage, adjusting the speed, trimming the clips, navigating around the edit etc, it lags heavily. The movie is now around 20 minutes long and when I bring in new clips it is almost not usable. Opening and closing the 4K files outside of iMovie is flawless.
Why is this happening? Is iMovie just not man enough? I haven't experienced lag with anything before and have run some demanding games on full graphics etc.
I recently made an edit which was filmed with an older GoPro only at 720p. iMovie still lagged when quickly chopping up clips and adjusting speed of clips.
Any help would be appreciated.
MacBook Pro 14″, macOS 13.0