It's not NTFS that's slow, it's something in the Windows I/O subsystem common across file systems. And it's not that it's slow on small files (the I/O performance is fine), but that there's a large overhead for repeatedly opening and closing files, especially by paths. Apparently Linux gets around this with some sort of inode cache (hashtable?) whereas Windows doesn't implement this for whatever reasons. (Possibly the filter drive model used to support virus scanning etc. doesn't allow it, though I don't quite understand the details of why.) Not even sure Mac is as fast as Linux in this regard.