A named pipe will not change the buffer size. The way pipes work (both anonymous and named) is they send data in groups that are exactly as large as they came in.
So probably something is using the write function with just one character at a time. The standard wrapper over write (i.e. the stdio functions like puts and printf) can be set to buffer the data first then write it out.
So probably something is using the write function with just one character at a time. The standard wrapper over write (i.e. the stdio functions like puts and printf) can be set to buffer the data first then write it out.