You can use a bottom cleaning bit (they make some pretty wide ones) for cutting tenons quickly (2 passes instead of 6) on each side. If you are going to be doing a lot of them, it might be something you would like to invest in. A sample is at the site below. Either a sled or a large backer block will keep your tenons square.
http://pricecutter.com/html/catalog/productGroup.asp/487
http://pricecutter.com/html/catalog/productGroup.asp/487
