When working on character encoding issues for the Texinfo parser I found that the run time of makeinfo would be slower when a UTF-8 encoding was used.
Running "makeinfo elisp.texi" (the Emacs Lisp manual) runs in about 49 seconds on my computer. When I comment out the "@documentencoding UTF-8" line this comes down to about 40 seconds. I haven't found a way to make using UTF-8 as fast as not. I expect the speed difference is due to the way Perl processes UTF-8 strings internally.
