Synchronous WSGI workers block on I/O preventing concurrent request handling

Default synchronous WSGI workers in Gunicorn are blocking; when a thread waits on external I/O operations (database queries, API calls), it cannot handle other requests. This drastically limits concurrency compared to asynchronous workers. Callbacks exceeding 500ms in high-concurrency environments significantly increase worker saturation risk.

Switch to non-blocking worker types (Gevent or Eventlet) for I/O-heavy dashboard applications. Gevent workers use cooperative multitasking and can handle thousands of concurrent requests while waiting for I/O. Alternatively, migrate to ASGI framework (Uvicorn/Hypercorn) for native async support. If staying synchronous, move long-running tasks to external worker queues like Celery.