But cold start time. This article claims their cold start time is only one or two milliseconds. Lambda's cold start time is orders of magnitude slower.
If you have a 100 function chain w/ 100ms cold start times in between, then that's a nightmare, but for us, we're monolothic so all our cold starts are bundled together. In the end I can't truly benefit from the 1-2ms. I suspect so many teams are in the same boat. But I do lose a lot w/o the debugging and ease of testing that come with monolithic applications.