flutter - 为什么 Future.delayed(Duration(microseconds:n(ps:n<1000)),fun) 比 Future(fun) 快？

Question

这是我的代码。我查看了Future.delayed & Future的源代码。Future和Future.delayed都执行Time.run。Future Duration 是Duration.zero，但 Future.delayed(Duration(microseconds:n(ps:n<1000)),fun) 更快，有趣的是当 n >= 1000 时它会反转。

void event(){
  print("Future delayed start");
  Future.delayed(Duration(microseconds:999), (){
    print("Future delayed end");
  }).then((value) => {
    print("Future.delayed.then")
  }).whenComplete(() => {
    print("Future.delayed.whenComplete")
  });

  print("Future start");
  Future((){
    print("Future end");
  }).then((value) => {
    print("Future.then")
  }).whenComplete(() => {
    print("Future.whenComplete")
  });
}

这是输出。

flutter: Future delayed start
flutter: Future start
flutter: Future delayed end
flutter: Future.delayed.then
flutter: Future.delayed.whenComplete
flutter: Future end
flutter: Future.then
flutter: Future.whenComplete

提前致谢。