Slow burn speed device buffer

[Arun]

I have found that 2 disks of the same media type, TDK 50GB BD-RE DL; one would burn at 2X, and the device buffer stays at 94%. The second one would burn at 1X and the device buffer stays at 50%. why? And what can I do to the second disk to burn at 2X?

[LIGHTNING UK!]

Format it without spare areas.

[Arun]

I found that if I turn fastwrite on, it burns at 2X. Which is better, turn fastwrite on or format without spare areas?

[LIGHTNING UK!]

Format without spare areas.