I bet quite a lot, probably at least 10-50 per second without doing anything special for performance, i.e. multiple queries per alert, calling different APIs, things like that. I don't know of many places that are dealing with alerts measured in "per second" as a unit.

Not to mention that having multiple components doesn't mean it's "scalable" by default, it could happen that some part of the pipeline doesn't like multiple instances of something.