[tex4ht] problem with slow compilation of large latex file with large math content

[Karl Berry]

                     make:htlatex()
                     make:htlatex()
                     make:htlatex()

P.S. The texi2dvi script implements one way to check how many runs are
needed: it compares auxiliary files and keeps running TeX until they
stabilize.  I suspect latexmk and others do the same thing, though I've
never looked at them.  So it is doable, though far from trivial.  -k