partial diffs vs single global diff

[corollari]

Method 1:

On every new change:

1. Store the diff between the current tree and the previous one.
2. Replace the previous tree with the current one.

On restoring:

1. Walk back the array of stored diffs and apply them back.

Method 2:

On every new change:

1. Store the diff between the current tree and the one created when start was run

On restoring:

1. Use the last diff to restore the current tree to its original state (or just replaced the current tree with the original one).
2. Calculate which change would be the last one applied if the revert was to be carried.
3. Apply the diff of the selected change to the current directory, so as to bring it forward in time to when the revert has dictated.

Which one is better?

I'm not totally sure which one of the is the fastest one so that should be investigated. So far, I've implemented method 1.