A long-running app imported 7x slower than a freshly restarted one, the finding that beat every API optimization, plus runnable benchmark jobs.

The low-level Commerce DTO API is not automatically fast: counting the database round trips per imported row, and four fixes I would apply first.

Committing a 250,000-row Optimizely catalog import row by row, returning a per-row failure report, and coalescing catalog events into one per batch.

Upserting a catalog entry through CatalogContext and MetaDataPlus: ContentGuid, the meta class seam, response groups, and a create path that rolls back.

Why bulk catalog writes in Optimizely Commerce belong on the DTO API rather than IContentRepository — measured 2.7-3.3x faster, and what it costs you.