What are the purpose of the .history file?

What are the purpose of the .history file?

When opening a project the .history file is loaded and the memory usage doubles.

If I delete the .history file, Ardour says it cannot load it, but no harm seems to be done… and the project loads with half the memory footprint.

What are the actual content and purpose of the .history file? And is there a good reason for it to be taking up so much memory?

it allows you to undo back past the point where you started ardour.

we are working on ways to reduce the size + impact of these files.

Would it be possible to disable them i.e. in the Options window.
I personally never use undo after a save, since I use save as a sort of milestone denominator.

I have posted a feature request for the disabling of the .history file in Mantis.