Bingo! Thank you both very much and a special thank you to svdl for the clear description how to resolve the issue.

My page file was 2047 MB, obviously too small. Checked with Vue d'Esprit too and found that Vue uses 100% of the processor capacity while rendering. Poser 6 obviously doesn't support hyperthreading.

If you ever are in Basel, Swiitzerland send me an email, I owe you a beer or two ...

Regards,
Christoph