dart2js: 10x worse performance in lzma than DDC

import 'dart:html';
import 'package:lzma/lzma.dart';
void main() async {
  await Future.delayed(Duration(seconds: 1));
  var t0 = DateTime.now();
  for (int i = 0; i < 10; i++) {
    lzma.encode((("ASDF$i" * 10).codeUnits));
  }
  var t1 = DateTime.now();
  document.body.text = "dt: ${t1.millisecondsSinceEpoch - t0.millisecondsSinceEpoch}";
}