Debug mode enables additional checks (such as asserts) that don’t run in profile or release builds, and these checks can be expensive. Debug mode also executes code in a different way than release mode. The debug build compiles the Dart code “just in time” (JIT) as the app runs, but profile and release builds are pre-compiled to native instructions (also called “ahead of time”, or AOT) before the app is loaded onto the device. JIT can cause the app to pause for JIT compilation, which itself can cause jank.