Unbelievable slow speeds when burning DVDs

[Vasileios Gkanis <gkanis@cems.umn.edu>]

Hi, 
I have a laptop and I am running KDE 3.4.1 on love-sources 2.6.12_rc6. I am 
using K3B 0.12 to burn DVD/CD discs and everything is fine when I burn a CD. 
But, things are really slow when I burn a DVD, and the average speed is 
~0.5x. It takes about 1 hour to burn 3GB of data. What bothers me is that the 
hard disk is not sending data all the time. The transfer rates oscillates 
between 0 and ~4MB/s (roughly 2x).
Is this behavior due to a problem with the IDE driver or because growisofs 
does not support the DVD burner. 
I am using growisofs 5.21 and the DVD burner is a QSI DVD+/-RW SDW-082.

Now, in windows, with Nero, I burn at about 4x and it takes roughly 10min to 
burn 3GB.

If you need more informations about my system, please do not hesitate to ask. 

Thank you,
Vasilis