MacBook Pro 14 M1 Max lagging when editing 4K videos in iMovie

Hi,

Lagging can be caused by several things. You might want to contact Apple Support and talk to the techs there, as they have the capability of remotely accessing your computer that we cannot do here.

Meanwhile, you can try exploring some diagnostics. The common denominator is Go Pro, so there may be something about the Go Pro settings or the way it renders its vids.

Here are some things that you can look into before contacting Apple Support:

Shut down and Restart your computer: Often this simple procedure will cure things.

Delete preferences: Try deleting preferences, as that procedure often cures issues. To delete preferences, open iMovie while holding down the Option and Command keys and selecting to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects.

New project: Try creating a new project and see if the lagging is eliminated there.

Open iMovie in a new library: Try opening iMovie in a new library and importing your footage into a new project.

Space: Check to confirm that you have enough space on your application drive for iMovie to function efficiently.

Format and frame rate: What are the format and frame rate of your clips? iMovie supports 4k 30 fps, so if you have a much larger frame rate that might cause some lagging.

Activity monitor: Check your Activity Monitor (Applications/Utilities/Activity Monitor) to see that there are no other cpu intensive programs running.

Hardware check: Run your Mac's Hardware diagnostics to confirm that there is no hardware problem, like defective RAM or failing graphics card.

-- Rich

There's got to be some explanation as to why the audio goes out of sync in just certain parts of the project. Sometimes having clips with different frame rates in a project can cause problems. If you have different frame rate clips, possibly exporting the project without the audio and then running the exported movie through Handbrake to give it a single frame rate might help. Then import the converted movie back into a new iMovie project and add the audio. Maybe that would fix the sync.

-- Rich