From the source
Amp reads the diff, identifies the files that are essential to the change, and puts them first.
If the diff changes, Amp computes an updated order without rearranging the files while you’re reviewing them.
Instead, a blue dot will appear over the intelligent ordering button, which you can click to apply the updated order.
The new automatic intelligent ordering is computed much more rapidly.
Here is a comparison of the same diff ordered by both the old and new method: You can optionally go back to alphabetical file ordering by clicking the ordering button.