i think my HDD could be the bottleneck. it is reffered to as "slow", but couldn't find any real life numbers. it is an Maxtor DiamondMax 30 VL 32049U3. but it still doesn't explain why it takes an hour to burn a DVD at 4x in Linux and in Windows it is finished in 17 minutes. disk performance in applications seems to be equal in both OSes. but now i remember, that xcdroast had the same problem (slowing down without any apparent reason). i just forgot about it. there must be something which is holding it all back. i will try to figure it out. it really could be an hardware issue, VIA apollo pro 133 were one of the worst chipsets around. thank you very much for your help. if i find out anything i will share the knowledge.