A user takes an iOS-based smartphone that is performing slowly to a repair shop.

Comprehensive and Detailed Explanation From Exact Extract:

When an iOS device approaches full storage capacity, performance can be significantly impacted. iOS requires a buffer of free space to perform background processes efficiently.

From theAll-in-One Exam Guide:

“iOS devices need several gigabytes of free space to maintain optimal performance. Near-full storage can cause sluggish operation and failures in updates or background tasks.”