This is addressed in the article:

> “But Rob,” I hear you say, “they’re not reading it byte-by-byte in the PHP version!” and I’d reply with, “but we’re not reading it byte-by-byte in the C# version either!”

C# also reads in 4K chunks: https://github.com/dotnet/runtime/blob/1ba0394d71a4ea6bee7f6...

That just means there aren’t 4K times as many file read ops.

The read() calls (which most of the time just increment the index into the buffer and returns what’s there) are still made.

The usual way of doing what he’s trying to do will look exactly the same in C# as in his php version, with explicit buffering.

You can follow the link to the underlying C# library where it is reading it in 4kb chunks as well. PHP doesn’t buffer for you, so if you want to read a file one byte (to your peril) at a time, you can. It’ll be as fast as the async version of the C# implementation, but still slower than reading buffered.

Both of these programs will make the same I/O calls but the total number of method invocations will differ by a factor 4096 unless I’m mistaken (it’s late). Those are cheap, but not free.