Under high webhook load: 90s+ delays with executions stuck in 'new' status; workflows unresponsive (no logs/errors, needs restart); production URLs return Internal Server Error (tests work); trigger nodes fail to register; queue length >50, latency >300ms.

By design, n8n processes incoming webhooks in parallel with no default limit on concurrent production executions or rate limiting on receipt, causing Node.js event loop thrashing, unresponsiveness, and failures under traffic spikes. Concurrency controls only queue post-receipt executions, not preventing initial overload.