What impact does Magento 2's indexer mode have on bulk import performance and frontend data freshness?

Goal: Determine whether keeping indexers in Update on Save mode during bulk product imports creates a measurable admin response time bottleneck that outweighs the risk of stale frontend data when using Schedule mode.

Constraints: The store runs Magento Open Source 2.4.5 in production mode, cron is configured to run every five minutes, and the admin panel is used by multiple operators importing CSV files of up to 2,000 products. Switching indexer modes requires cache flush and may cause temporary data inconsistency if not reindexed.

Uncertainty: It is unclear if the increased admin latency from synchronous reindexing during bulk imports is significant enough to justify switching to Schedule mode, given the potential for inventory or pricing stale data until the next cron run.

• What is the average increase in admin save time per product when indexers are set to Update on Save versus Schedule during a bulk import of 1,000 products?
• How long after a bulk import does frontend inventory or pricing remain stale when indexers are in Schedule mode with a five‑minute cron interval?
• Does enabling asynchronous indexers via message queues (available in Adobe Commerce 2.4.2+) mitigate the admin latency without reintroducing noticeable frontend staleness?