Free extensions for Joomla!

XMap is working on our system with Joomla 2.5.8 and Virtuemart 2.0.12f very good.
The only issue we have is that the sitemap xml is generated very slow, when we add the product links to it.

without products, but with content and VM categories:
82 urls are displayed in about 1,5 seconds

with products, content and VM categories:
450 urls are displayed in about 118 seconds

Is there anything we can do to speed it up or is this a known bug?

Regards,
Michael