> I had created a global variable before like this:
> 
> 
> But it did not improve the transformation. 
> 
> Then I decided to try the For-each loop but to no avail.
> 
> What do you thing about using keys?
> 

This was the only construct I could see that looked potentially inefficient.
There is nothing in your stylesheet that would benefit from keys - it's not
doing any searching. If this doesn't help, then I suspect David is right and
the problem is in rendering the HTML, not generating it.

Michael Kay
http://www.saxonica.com/