Because the A15 chip is actually faster than the M1 chip. The original file was an: 8K IPB 29,97 fps MPEG-4 film with a duration of 1 minute and 54 seconds. The output file was 4K 29,97 fps Apple ProRess 422 with the format Quicktime (.mov) A15 chip export time: 2 minutes and 20 seconds. M1 chip export time: 3 minutes and 32 seconds. More @Wikipedia
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