Why does Xalan not use DOM's getElementsByTag method?

[Turaukar Yur]

I have a pretty large XML Schema where certain tags may have many many 
different children, e.g.
<A>
  <B1>...</B1>
  <B2>...</B2>
   ...
  <B99>...</B99>
</A>
Running a style sheet with many xpath expressions value-of select="A/Bnn" 
where nn is a number is very inefficient with Xalan.

To improve performance, I have decided to parse the data into my own DOM 
implementation, that supports quick access to a given child tag by name, 
i.e. a very fast implementation of getElementsByTagName.
To my surprise, Xalan seems to ignore this method and "prefers" to iterate 
all child elements of a tag whenever it searches for a specific child 
(getFirstChild+getNexSibling).
Am I missing an important point here? My solution really relies on a quick 
access to given elements.

Thanks for feedback
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