[xml] does xsltproc caches subexpressions

[Stefan Kost <ensonic hora-obscura de>]

hi,

in oder to speedup gtk-doc I made a patch to replace xslt by perl for
the docbook index generation [1]. Still there is some bias of others
towards the xslt version.
The slowness has been tracked down to some specific operations (its all
in bugzilla). Is there room for optimization on the libxslt level here?
Does or can it cache intermediate result to avoid double evaluation?

Stefan

[1] http://bugzilla.gnome.org/show_bug.cgi?id=311857