probably a bit of loose wording there. It's probably not what either of us would call objectively rare, but it is comparatively rare compared to many other runtimes. There's quite amount of this that can be avoided with some vertical or horizontal scaling depending on what you are doing with these events.

For instance you linked the spring application events integration with redis, while that is definitely an option it's not one you'd immediately reach for. Instead you'd more likely set up and use application events and/or domain events (if using spring data) handled locally with thread pool. The benefit here is that of course way less set up and complexity, but you can also handle these events sync or async.