Shopify gives your webhook endpoint 5 seconds to respond. Miss it and the delivery is marked failed. Under load, that window disappears fast. I have seen well-built Shopify apps completely fall apart during a product launch — not because the logic was wrong, but because everything was running synchronously inside the handler. This post breaks down how to fix it properly. The Core Problem A single orders/create event can require: Inventory sync Fulfillment creation External ERP update Customer notification That is four operations, each with their own latency and failure modes, all competing inside a 5-second window Shopify is actively timing. During a flash sale, hundreds of these arrive per minute simultaneously. Synchronous handling does not survive that.…