XSieve can instantiate parts of the SXML tree on demand. If making an SXML tree is a very slow operation, then the lazy instantiation might be a performance improvement. Unfortunately, it seems that XSieve doesn't benefit of the lazy binding.
Anyway, the lazy instantiation feature is still supported. To activate it, follow the procedure.
Procedure B.1. Installing XSieve with lazy tree instantiation
Install Scheme interpreter Guile with the lazy pairs patch. The process is described in Section B.1, “Installing Guile with the lazy pair patch”.
When running the XSieve configure script, specify the parameter --with-lazy-guile-prefix. The value is the path to the installation directory of Guile with the lazy pairs patch.
Find and download the source tarball (guile-lazypair-X.Y.Z.tar.gz) from the XSieve download area for lazypair.
Select an installation directory. I recommend to use something like $HOME/opt/guile-lazypair.
Follow the standard way of installing programs:
$ tar zxf guile-lazypair-X.Y.Z.tar.gz $ cd guile-lazypair-X.Y.Z $ ./configure --prefix=$HOME/opt/guile-lazypair $ make $ make check $ make install
If you want to check that the lazy pair patch works, download the archive guile-lazypair-test.tar.gz from the XSieve download area for lazypair. Instructions are inside the package.
For more information on the patch, see the web page "Lazy pairs for Guile".