Saxon

Another streaming question. I'm testing extracting some data from the beginning of a very large file (>3GB). I'm using the following instruction:

<xsl:stream href="enwiktionary-20140102-pages-articles.xml">
  <xsl:iterate select="mediawiki/page">
    <xsl:copy-of select="."/>
    <xsl:break/>
  </xsl:iterate>
</xsl:stream>

(the source file is available from here: http://dumps.wikimedia.org/enwiktionary/20140102/enwiktionary-20140102-pages-articles.xml.bz2)

It's my understanding that this code should halt after encountering and copying the first page element from the the source file. When I run the stylesheet against a small sample file, I do indeed get just the first page element as I expect. When I run against the full document (which has a page element about 100 lines in), I see four of my cores go to about 50% and stay that way for more than 10 minutes. I've never actually managed to get it to finish execution. Is this normal?

I've attached the stylesheet and simplified sample file.