The performance is breathtaking. The A7 chip on iOS 7 is a match made in heaven. Unlike the bogged-down experience of iOS 12 on the same hardware, iOS 7 flies. Animations are snappy, multitasking is instant, and the UI feels incredibly responsive. There is no keyboard lag, no stuttering when opening Control Center, and the translucent blurs of the user interface render smoothly. You are also greeted by icons that have since changed—Passbook (before it became Wallet), the old skeuomorphic Compass, and the distinct blue/green gradients of the default apps.

In the modern era of iPhone security, downgrading is usually impossible. Apple stops "signing" older firmware versions usually within a week or two of a new release. Once the signing window closes, the device refuses to install the older software.

but requires the device to be connected to a Mac/PC to boot up if it ever loses power. Untethered Downgrade (Blobs Required):

The iPhone 5s introduced the Secure Enclave Processor (SEP). Even if you bypass the main software check, the SEP must be compatible.

The iPhone 5s originally shipped with iOS 7.0. However, downgrading from a newer iOS version (10.3.3 or 12.5.7) back to iOS 7 is and is technically impossible using standard methods due to cryptographic signature checks. This report outlines the only known bypass methods, their severe limitations, hardware dependencies, and success rates.