For a remote file with a slow connection, the file saving can take some time, even for small files. And the buffer is blocked from any modification during the file saving.

For small files, it is possible to:
1. retrieve the entire content of the buffer into a string
2. save the string asynchronously

With step 1, we have a snapshot of the buffer contents. So any further modification is not taken into account, and the saved file is in a consistent state. Since the long string is in memory, the first step should block the buffer only for a short amount of time.

For big files, it is unfortunately not possible to not block the buffer while saving. So the autosave setting should be disabled in this case.