In a FaaS environment, the functions should be kept as light as possible. Loading many explicit or implicit external dependencies (when a library you reference loads many additional modules it relies on) can increase the function load time and even cause timeouts. Thus, functions should keep their external dependencies to a minimum.
In addition, in most FaaS environments, functions face a significantly increased cold start latency. After a period of inactivity an unused function goes idle. The next time the function is loaded, compute and memory will need to be allocated to it, external dependencies will need to be loaded, and, in the case of compiled languages like C#, the code needs to be re-compiled. All of these factors ...
