JIT (Just-In-Time) compilation is a technique that allows certain programs to run significantly faster by compiling code at runtime, rather than ahead of time.

Apple enabled this for iOS 14+, but killed it again with iOS 17. It's basically the reason why we currently don't have full speed VM's on iOS / iPadOS devices.

While Sideloading / Altstore / Sidestore allows you to install any IPA, this still doesn't enable JIT for these apps. There are currently some workarounds that involve running certain software on your local network (search SideJITServer on Github).