How many properties do you have indexed in your entities, and how many custom indexes do you have?
Alfred gives a good example of how writes are calculated for new and updated entities here - https://groups.google.com/d/msg/google-appengine/mjnSqQWOfqU/cgPVeHbrR8oJ -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To view this discussion on the web visit https://groups.google.com/d/msg/google-appengine/-/GZjRc2EANUoJ. To post to this group, send email to google-appengine@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.