Replace your iPhone battery

If your old iPhone feels slow and sluggish, it might be because the battery is too old. Replacing it will improve the performance of your iPhone instantly.

A post on Reddit said that iOS will purposely slow down a phone when the battery shows substantial wear. I have a 3 year old iPhone 6+. I measured the battery condition using coconutBattery from my Mac. The battery was down to 75% of design capacity after ~750 cycles. I then ran Geekbench for iOS. The benchmarks were about 1000 for single-core performance, and 1800 for multi-core. They should be 1460/2459 respectively. Finally, I installed CPU DasherX on my phone. Down towards the bottom it reports the CPU frequency. It said 839MHz for my phone, but it should be 1400 MHz.

I went to a local place to replace the battery for $50. Now all my numbers are as they should be. The phone works perfectly well. I almost bought a new phone because this one had turned sluggish. I just saved myself $800 for a phone I didn’t need.