Not to get too off topic but i have not experienced a speed problem. I have burnt several DVD+RW disks at 4x and only one DVD+R at 8x (I horde them as I am currently unemployed) with no problems. I haven't switched to the 2.6 kernel series as I have had problems with my sil3112 raid setup. My LFS 6.0 install is on a regular IDE drive and is using the 2.6.10 kernel but I haven't really used it for anything atm.
(EDIT) I apologize, I guess when I actually watch the burn the buffer is emptying. I guess i should have paid more attention. I just tried to burn 3.9gb at 8x and its choking. BTW though at 4x the speed and time were right on..... Guess I will be more serious about upgrading to a 2.6 kernel.