The transfer buffer is not a problem (if you get slowdown in actually reading the directory, the reason is probably the amount of data is huge and you have slow

The transfer buffer is not a problem (if you get slowdown in actually reading the directory, the reason is probably the amount of data is huge and you have slow i/o). The problem is when ls then tries to do all kinds of things after reading that data in order to sort, columnize, colorize, etc. For example, just figuring out if you should add / after filename to indicate directory can, in worst case, require stat() call on every returned file - because there's no guarantee that file type will be filled in response from readdir()/getdents(). Sorting and displaying in columns is particularly slow. All sorts of things that are nice to have, cheap quality of life benefits, breakdown and become huge slowdowns with such insane directories.