My estimable Twitter-pal Paul Johnson has put together a very reasonable thread about his thinking on serverless costs (ie. AWS Lambda, in this case). He makes a great case for the design of functions being done in such a way as to allow cost efficiency improvements, and I think the point on architecture is generally well-made. However, there are a few aspects of this which I think are generally not well understood, and Twitter is much too short a form to get them in. Hence this post.