How to Monitor CPU, Memory and Thermal State on iPhone (and What iOS Won't Let Any App See)

TL;DR

System Info charts live CPU (including per-core), memory, battery and thermal state, plus device model and iOS version. iOS hides other apps' processes, so only the app's own activity can be measured; it shows load and heat, not who caused them.

The problem

The phone is hot and sluggish, and iOS tells you nothing. Is something hammering the processor? Is memory short? Or is it just a hot day? Without data, all you can do is restart and hope.

What System Info shows

  • Live CPU load and per-core load charts
  • Memory use
  • Battery
  • Thermal state: how hot iOS thinks the device is
  • Device profile: model, iOS version, core count and uptime

How to read it

  • Thermal state rises when the phone is working hard or sitting in the sun. When it gets high, iOS slows things down to cool off, which explains stutter.
  • Load spread across cores vs. one pinned core tells you whether work is balanced.
  • Memory near the top explains apps reloading when you switch back to them.

An honest limit

iOS does not let an app see other apps’ processes. The System Info screen says this itself: only this app’s live activity can be measured on the device. So you can see that the phone is under load or hot, but not which app is responsible. To find a culprit, use iOS’s Battery screen for usage over time.

Practical steps if it’s hot

  1. Stop charging and heavy tasks for a while.
  2. Take the case off and get out of direct sun.
  3. Check the thermal state again after a few minutes.

FAQ

Can it tell me which app is slowing my phone? No. iOS doesn’t let apps see other processes, so it shows overall load, memory and thermal state, not a list of apps.

What can I see? Live CPU and per-core load, memory use, battery, thermal state, and device details like model, iOS version and uptime.

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