为什么Flutter（飞镖）处理图像的速度如此之慢？

我有这种方法，可以将用户手机中的照片加载到内存中，调整大小并将其编码为JPEG：

I have this method, that loads a photo from the user's phone to memory, resizes it and encodes it as JPEG:

List<int> processPersonProfilePhoto(File file) {
  var rawPhoto = file.readAsBytesSync();
  var jpg = Image.decodeJpg(rawPhoto);
  jpg = Image.copyResize(jpg, 512);
  return Image.encodeJpg(jpg, quality: 70);
}

我正在通过以下方法在单独的隔离上运行上述方法：

I am running the method above on a separated isolate, via:

var jpgByteArray = await compute(processPersonProfilePhoto, file);

整个过程有时需要20到30秒（发布模式比调试还要差），我

This whole process sometimes takes 20 - 30 seconds (the release mode is even worse than debug) and I am running on middle and high end devices.

这是我正在处理的软件包：

This is the package I am using to process:

image: ^2.0.7

我在做什么错？

PS .：我做了更多的调试工作，并意识到需要花费更长时间处理的那行是去尾的：

PS.: I done some more debugging and realized that the line that takes much longer to process is the deconding one:

var jpg = Image.decodeJpg(rawPhoto);