Fan-Out/Fan-In Pattern Boosts Async HTTP Throughput 10x

A developer demonstrates how fan-out/fan-in orchestration can process 500 independent order line items in parallel, reducing wall-clock time from ~90 seconds to the duration of the slowest single item. The pattern uses Task.WhenAll to schedule all activities at once and aggregate results, surviving orchestrator replays. Sequential processing achieves ~5 activities per second, while fan-out targets ~100 per second per instance.