Looking closer at the debug memory graph it seemed that the autoreleasepool holding the audio buffer was too long-lived. I've not worked closely with these pools before but I was able to solve the memory issue by closely wrapping the conversion call in its own pool: _ = autoreleasepool { converter.convert( to: outputBuffer, error: nil, withInputFrom: converterInputBlock ) } This appears to correctly scope the lifetime of the buffers. If anyone has a good explanation for this I'd love to hear it!

This turns out to be either a misunderstanding of, or possibly a bug in, the way DifferenceKit interacts with a view-based, rather than objectValue-based, NSTableView. I was crucially not checking the values with which reloadData(forRowIndexes:columnIndexes) was called, and the columnIndexes passed by DifferenceKit's algorithm were always [0], which was not valid for any visible cells as my first column is hidden, so the methods weren't called. The useful lesson here is that when a tableview's delegate lacks tableView(_:viewFor:row:), a reload to any column reloads the entire row, but once views are specified, the column values become relevant.

I have the same issue, with Swift, in 2022.