Your kernel most likely didn't apply optimal settings for your drive when it detected it. You can find out what are the current settings of your drive with the command

hdparm -v /dev/dvd

/dev/dvd:
 IO_support   =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  0 (off)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    = 256 (on)

The following options are known to maximize burning and playback performance:

hdparm -d1 -c1 -a8 -u1 /dev/dvd

To make these options permanent, a quick and dirty solution is to include the command in /etc/rc.local. Consult your distribution documentation for a tailored solution.
Some drives have buggy DMA support. If you experience instability, leave these options disabled.
Some useful references:
http://www.togaware.com/linux/survivor/CD_DVD_Drives.shtml
http://www.linuxjournal.com/article/6921