SAP Cloud SDK for JavaScript 4.0 turned destination caching on by default for lookups made through the destination service — getDestination(), getAllDestinationsFromDestinationService(), and the generated client's execute() all now cache what they resolve. Before 4.0, every one of those calls re-fetched credentials from the destination service; the same release also stopped requiring an XSUAA service binding to retrieve a destination and disabled iasToXsuaaTokenExchange by default.
Advice written before March 2025 that assumes every destination lookup is a fresh call to the destination service. A stale cached destination, not a slow round trip, is now the first thing to check.