I'm using EWS on an Exchange 2007 with basic authentication. I'm calling just the FindItems() method and the transaction log seem to grow alarmingly.
On my test server I ran an endless loop calling FindItems() and the logs grew with 1 MB per 5-6 minutes. In an production environment, calling this would cause a growth of 1 MB per 10-15 seconds!
Why does the transaction log grow when I only make read-only requests to the EWS?
It is possible the production server makes more logs. It is possible your test-server didn't log these events while the production server does. This is a setting. More info: http://www.msexchange.org/articles_tutorials/exchange-server-2007/management-administration/managing-exchange-server-2007-log-files-part2.html