This is not inherent to the patch model, just to Darcs' algorithm. Pijul (pijul.org) doesn't have these problems, and is indeed quite fast. The main limitation

This is not inherent to the patch model, just to Darcs' algorithm. Pijul (pijul.org) doesn't have these problems, and is indeed quite fast. The main limitation at the moment is merging very large histories, which has the same complexity as a Git rebase at the moment (this will be fixed).