Processing speed dropped from 7 fps to 1 fps mid-export

I’m working on a project where I am trying to upscale an older shot-on-videotape (i.e. interlaced) HD video that was originally encoded in Apple Intermediate Codec (see screenshot) at 29.97 fps to make it a 4K 59.94 fps file.

When I started the encode, I was getting processing rates of 7 frames per second and an estimated export time of 75 minutes. I came back to it about 2 hours later, and it’s still processing, with the export dropping to 1 frame per second. It’s only 70% done, and still has 150 minutes left.

What gives? Why would the export start that fast and then drop so precipitously? I’m on a 2021 MacBook Pro, M1 chip with 32 GB of RAM.

Screenshot 2024-03-16 at 8.16.03 AM
Screenshot 2024-03-16 at 10.58.33 AM
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Screenshot 2024-03-16 at 11.03.54 AM

Total time ended up being 3 hours & 41 minutes.

If you were processing with the model settings on Auto, adjustments made during export could be the reason for the speed change.

What’s the storage you are using? That sounds like what happens when my SSD cache gets filled.

I am using the SSD on the MacBook Pro.

Since that SSD is soldered onto the motherboard, and no one seems to have done the kind of testing I am thinking of on such a Mac book, I cannot know how your SSD will act once the cache is filled—or if the cache can even be filled.