Flutter App Performance Optimization

I am working with a ready-made Flutter application (source available here: https://shareapi.in/fileDetails.php?fileId=20250920142035q3j5uktl96hnn8z) and need help resolving the performance bugs that are holding it back. Right now the build struggles with slow loading screens and noticeably laggy animations; frame rate dips below a usable level and the overall user experience feels sluggish.

What I expect from you: profile the code, pinpoint the bottlenecks, and refactor or replace problem areas so the app holds a smooth, consistent frame rate—no more of those sub-20 fps drops. I am not adding new features or redesigning the interface; the sole focus is on fixing the underlying issues causing the delays and stutters.

You are free to use tools like Flutter DevTools, Dart Observatory, or any performance plug-ins you prefer, as long as the final build demonstrates clear, measurable gains when I run it on both Android and iOS simulators (and at least one physical device). Once the fixes are in place, send me the updated source plus a brief report summarizing the main changes and the FPS / load-time improvements you achieved.