Thanks for all Peter,

generating a sitemap of 150.000 in a single operation is usually impossible, it would take too much time, especially if you are using third party extensions such as Virtuemart.

For this reason has been developed the AJAX generation and precaching of the XMl sitemap.
This allows for incremental generation of very large sitemaps avoiding timeouts.

You find detailed instructions to use it in the pdf documentation.

Best regards!

John