Will IOS 27 make old iPhones slower?

Probably yes — major iOS updates can make older iPhones feel slower, but we can’t know exactly what iOS 27 will do yet because its features and hardware requirements aren’t known now.

In general, big iOS updates can make older phones feel slower for a few reasons:

• New software may be more demanding and run better on newer chips and more RAM.
• Right after an update, the phone may spend time reindexing files and finishing background setup, which can make it feel warm or sluggish for a while.
• If the battery is worn, iOS may reduce peak performance to prevent unexpected shutdowns.

What to do if you have an older iPhone:

• Check Settings > Battery > Battery Health & Charging.
• If the battery is degraded, replacing it can improve performance.
• Keep some free storage space and give the phone time to finish post-update tasks.

Short answer: iOS 27 could make some older iPhones feel slower, but the effect would depend on the specific model, battery health, storage, and the final system requirements.