Hello,

i should understand better what it means 'server goes down', i mean timeout, memory limit exceeded, etc, in most cases this happens when sitemap contains too much links to be processed in a single operation compared to server resources. But this usually happens when sitemap contains 20000 or 30000 links at minimum.

If you experiment issue with only the virtuemart categories it souds weird, eventually contact me at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it to send me credentials to have a deeper look.
The SQL generated query is standard, so i don't think it could be the problem.

Best regards

John