as others seem to have burning speed problems with growisofs / k3b, too, you may have a look at my KDE bugreport:https://bugs.kde.org/show_bug.cgi?id=120548 Maybe that helps,
Not if you complement the report with dvd+rw-mediainfo output preferably for resulting recording or at least for same media brand. In other words dvd+rw-mediainfo output is a *requirement* for meaningful problem report. Cheers. A.