speed up xslt

Hi,

is there any way to speed up xslt transformation in php4/5?
I heared that it is generally a good idea to compile a stylesheet
into memory if you apply small number of stylesheet to
many xml documents, and that is exactly what I want to do.

Is there a way to improve xslt speed by loading an xslt style-
sheet into memory, serialize it to the harddisc or anything
like this?

I don't want to $xsl->load('my.xsl') hundreds of times...

Marc