On a 100,000-product test store on MariaDB 10.5, Magento took 3.5 hours to rebuild the category-products index; with two database settings changed, 12 seconds. Index Doctor checks for that and everything around it: the database's version and settings, the InnoDB buffer pool, temporary tables, indexes that need a rebuild or are stuck "working" after a crash, index modes, waiting changelogs, a cron that isn't running. Each finding comes with its fix. Every reindex is timed, and a slower one is reported. It needs nothing else from Zero: any Magento 2.4.7–2.4.9 store, any theme.
System > Tools > Index Doctor: the findings, the worst first, each with its fix.
What it does
Database version and settings, buffer pool, temporary tables
Indexes to rebuild, stuck reindexes, cron
Each finding with its fix: bin/magento zero:index:doctor and the admin
