Testing workflow with GoPro 4 Black, Macbook air and iMovie.
GoPro was in default settings with picture taken every second. That was bit too much so I used every 5th picture. Importing that many pictures in one time was slow in macbook air. So I made movies which had about 500 pictures each. I made pictures crop to fit scale and changed the lenght to 0,1 sec which is minimum. With these settings movies are about 1 min and 5 sec long. These movies are imported into new movie in imovie. This movie is saved in 2x speed which makes one frame somewehre around 0,05 sec. To my eye this seems nice. Next stop all the settings in gopro, and there are a lot of them ..