Here's the simple answer. MC, when sharing files from server to client, needs to stream the files. But many file formats are not readily streamable. This means, the files have to be sent entirely to the client before the client can do anything - hence buffer and waiting.
If instead, your files are shared via Windows networking, the client MC can just read the files directly from the file system. MC does not have to stream the file.
You enable the client option to Use local files when available. You configure all your systems to access the media through the exact same path. Either all use UNC paths or the same Windows drive paths. E.g.:
M:\Media\....
\\NAS\Media\...
Since MC maintains Filename fields for each file, the client can just use that field directly, and start reading / playing the file. No buffer, no wait.
