VBCS performance — patterns that actually work at scale

After building 10+ VBCS applications with 500+ concurrent users, here are the patterns that consistently made the difference.

Pattern 1: Lazy-load service connections — Don't fetch everything on vbEnter. Only fetch what's visible in the initial viewport.

Pattern 2: Use SDP for tables — Built-in pagination and sorting is optimised. Manual REST calls for tabular data almost always perform worse.

Pattern 3: Variable scoping — Application-level for reference data, page-level for transactional data.

Pattern 4: Limit REST payload size — Always use the ?fields= parameter on Fusion REST calls.