Time Machine has improved a lot after the switch to APFS. Mostly because it supports full snapshots, with an easy way to get the difference between two snapshots.
The previous HFS+ version relied on directory hardlinks that were notoriously buggy and easy to corrupt. The difference computation also required basically recursively walking the entire tree and comparing the directory change times, with each lookup requiring a network round-trip.
The previous HFS+ version relied on directory hardlinks that were notoriously buggy and easy to corrupt. The difference computation also required basically recursively walking the entire tree and comparing the directory change times, with each lookup requiring a network round-trip.