Re: Emacs hangs on long words in .html files

[Richard Stallman]

    -(defconst sgml-namespace-re "[_[:alpha:]][-_.[:alnum:]]*")
    -(defconst sgml-name-re "[_:[:alpha:]][-_.:[:alnum:]]*")
    +(defconst sgml-namespace-re "[_[:alpha:]][-_.[:alnum:]]\\{,64\\}")
    +(defconst sgml-name-re "[_:[:alpha:]][-_.:[:alnum:]]\\{,64\\}")
     (defconst sgml-tag-name-re (concat "<\\([!/?]?" sgml-name-re "\\)"))
     (defconst sgml-attrs-re "\\(?:[^\"'/><]\\|\"[^\"]*\"\\|'[^']*'\\)*")
     (defconst sgml-start-tag-regex (concat "<" sgml-name-re sgml-attrs-re)
    ------------------------------------------------------------------------

    Whereas before it was taking 67 seconds to open a file containing a
    16,000 character 'word', I can now open the same file in about a tenth
    of a second.

Can someone please investigate why the search for
"[_[:alpha:]][-_.[:alnum:]]*" is so slow?
Is something badly implemented in regex.c?