Is asyncio Really Better Than Multithreading? I Tested 100 Concurrent Requests, and the Difference Is Huge

Last month, the data platform I maintain suddenly got a new requirement: run health checks against 100+ downstream services. Each endpoint averages 200ms, and the whole check had to finish within 5 seconds. Without thinking twice, I fired up 100 threads. The thread-switching overhead immediately maxed out the CPU, and the response time shot past 8 seconds. My ops teammate dropped three question marks in the group chat. That moment forced me to seriously re‑examine asyncio. I used to think async