As previously announced in the API Changes log, the time that it takes to receive an update for the auto_save webhook will decrease from 20 seconds to 5 seconds for content that has been changed in the Web App.

If you are consistently editing an entry in the web app for one minute, and you have a webhook configured to be called for auto_save events, that webhook will be called 12 times in a minute whereas previously the webhook would be called 3 times in a minute.

The Webhooks developer docs have been updated to reflect this change.