Re: struct.el -- a package to encode/decode binary data

[Richard Stallman]

    > Am I right in assuming that aref, aset, and substring are potentially
    > much slower on a multibyte string than on a unibyte string?

    If the string holds non-ASCII text, yes.  But not in your case, where the 
    ``string'' holds binary data, I think.

Multibyte strings are slower in this case.  The only case where they
are not slower is when the contents are all ASCII.

To see the slowdown best, try accessing the string nonlinearly.