All iPhones are slower than expected when new or after an iOS update, and indexing is generally the culprit. The short answer to speed up your iPhone is to wait—indexing all your data takes time, but once complete, searches feel especially fast. This applies to Spotlight and now Siri AI, which uses the index to retrieve emails, calendars, and files instantly.

The process can take hours or days depending on data volume, and Apple notes it may last up to a week in practice. Indexing occurs on-device and is continually updated, with initial setup being the slowest phase. Files, folders, apps, documents, emails, messages, contacts, photos, music, podcasts, notes, and system settings are all indexed.

You can monitor progress in Settings under 'Optimising Search and Siri,' which appears only during initial indexing. To help, leave the iPhone charging, connected to Wi-Fi, and avoid heavy use. The slowdown is temporary and resolves once indexing finishes, after which performance improves significantly.