Reduce headless checkout latency with Composite REST API patterns

• Batch related GETs into Composite REST subrequests reducing round trips • Use Composite graph for dependent writes: create order, payment authorization, inventory decrement in one HTTP call where supported • Move non-critical post-order actions—email, loyalty credit—to async queue after confirmation response • Implement BFF aggregating Salesforce and payment provider calls server-side near user region • Set aggressive timeouts with user-visible retry on idempotent payment steps only • Load test composite payloads at peak concurrency including auth token refresh overhead • Document partial failure handling when composite subrequest succeeds but sibling fails