The first weakness is warmup latency. Although the traffic managers of various platforms (AWS, Azure, Google Cloud, and so on) are very good at responding to demand when there are already instances of serverless code running, it's a very different problem when there are no instances running at all. The traffic managers need to detect the message, allocate a server, and deploy the code to it before running it. This is necessarily slower than having a constantly running container or server. One way to combat this is to keep your code small and simple, as the biggest slowdown in this process can be transferring large code files.