Yes, they also suffer from cold starts. When people talk about it, they usually measure the percentage of cold-started function calls, which mostly ends up bein

Yes, they also suffer from cold starts. When people talk about it, they usually measure the percentage of cold-started function calls, which mostly ends up being around 0.1% of all calls. In a sense, you have to have a good amount of baseline traffic to end up with that problem, which reduces the percentual impact. So the problem is less pronounced than with a function that is very rarely run, where a high percentage of function calls are cold. (In theory, the worst case where a CloudWatch trigger would be mostly useless is that a function is totally idle and removed from warm-state, and then gets a huge concurrent spike, is idle again, gets a spike etc. But that is not a realistic traffic pattern, I assume. It would also break with existing auto-scaling that would be even slower with bringing up new instances.)