DDC is not at all a representation of the final size of the code, as it doesn't run any kind of tree shaking, minification or optimization, and the animation library has a lot of things that you will definitely not import.

And here I am freaking about an uncompressed js payload of 300k for an entire app... 4+MB just feels crazy.

DDC stands for Dart Development Compiler. It is a fast modular compiler that you use for quick edit&refresh development in the browser. It does not do any global optimizations, unlike dart2js - which is what you use for deployment.

If you write something like:

    import 'package:flutter_web/animations.dart';

    void main() => print('Hello, World!');

DDC would faithfully compile animations.dart as whole and ship that to your browser.

dart2js would include 0 bytes of code from animations.dart into the output.

> `webdev build` failed for me in examples/gallery

Maybe file a bug?

Here is what I get for Gallery:

    ╭─~/s/f/f/e/gallery ⟨master ⟩ ⟨9s449ms⟩
    ╰─» flutter packages pub global run webdev build
    ...
    Compiled 18,344,245 characters Dart to 1,914,077 characters JavaScript in 27.9 seconds

If I gzip the output I get around 500k.

Gallery uses a lot of Flutter so this is in some sense upper boundary for framework overhead.

Also it is still early days - I can clearly see this pushed down.