Improve current loading time

I have a big files and it loads to me 3-5 sec to generate the md5 about the file. 

What do you think if you just check the mix-manifest.json updated at time?

```
 protected function getHashedName(): string
    {
        $manifestFile = dirname($this->path(), 2).'/mix-manifest.json';
        $hash = '?v='.filemtime($manifestFile);

        return $this->name().$hash;
    }
```