chunking very slow

[Peter Eisentraut <peter_e@gmx.net>]

I have embarked on converting the PostgreSQL documentation from DocBook
SGML + DSSSL to XML + XSLT.  The problem is that the XSLT to chunked
HTML build is very very slow, even with the fast chunking.

To give you an estimate of the size, the PostgreSQL documentation is
about 2500 pages in PDF.

Building with OpenJade and the DocBook DSSSL stylesheets takes about 3
minutes.

Building with xsltproc and the xhtml/chunkfast.xsl stylesheet without
customization takes about 18 minutes.  (With customizations to match
what I had with DSSSL, it takes longer still.)

But using xhtml/docbook.xsl to make one big HTML output file takes only
4 minutes.  So the chunking takes a lot of time.

The profile supports this:

number               match                name      mode  Calls Tot 100us Avg

    0                    *                    recursive-chunk-filename
                                                         110411 67768503    613
    1             footnote                    footnote.number
                                                             32 6365266 198914
    2              chapter                    label.markup
                                                           4238 4403825   1039
    3             appendix                    label.markup
                                                           1103 4345592   3939
    4                         gentext.template           590443 3319394      5
    5                                html.head             1115 2676209   2400
    6                            l10n.language           486089 2070452      4
    7                              href.target            23893 1255333     52
    8                                    chunk           368522 1119619      3
    9                     gentext.template.exists
                                                         450077 957036      2
   10                     inherited.table.attribute
                                                         110883 784757      7

Does anyone have any ideas how to improve this (other than by turning
off features such as chapter numbering, as suggested by the profile)?