Caching is another big one. Beyond the simplest of services you typically need to cache some info in memory, create connection pools, etc at startup to improve

Caching is another big one. Beyond the simplest of services you typically need to cache some info in memory, create connection pools, etc at startup to improve latencies. With serverless that is not possible without killing your cold start time. So it's hard to go serverless except for the simplest of applications.