[JoelJacobson]

> It works, but suddenly your query times explode! Instead of doing 1 million transactions per second* you can now do only 3 (*These numbers were exaggerated for dramatic effect)

In general, a single-queue design doesn’t make throughput collapse when you add more parallelism; it just gives you a fixed ceiling. With a well-designed queue, throughput goes up with concurrency, then flattens when the serialized section (the queue) saturates, maybe sagging a bit from context switching.

If instead you see performance severely degrade as you add workers, that typically means there’s an additional problem beyond “we have one queue” — things like broadcast wakeups (“every event wakes every listener”), global scans on each event, or other O(N) work per operation. That’s a very different, and more serious, scalability bug than simply relying on a single queue.