Now all forms are being saved every two minutes. You can find your autosaves in User Menu -> Drafts
If for some reason you did not submit a form, next time on the form page you'll see a prompt "Restore or Ignore". If you choose "Ignore" option, autosaved data will be deleted from the database permanently.
No saving happens while the Ignore/Restore popup is shown.
Please note that saved forms can't be restored if you re-login, so they're not meant to replace drafts.
This feature is still in beta testing. Please report any unexpected behavior/bugs.