[How to enhance my BD burn speed(12X)]

I have PIONEER BD-RW   BDR-S09(it shows support up to 16X for BD-R) and BD-R disc will support 12X.

But it takes me about 15 minutes to burn 18G data when i set the speed to 12X.

 

How can i enhance the speed ?

[How the Spare Area of DVD-RAM and BD-R/RE work.]

I have some question about Spare Area.

I know the DVD-RAM and BD-R/RE have the Spare Area. I want to know :

1, how them works?

2, when does the Spare Area be written? right after a defect found during writing, after all the write is finished and then write the spare area? same for DVD-RAM and BD-R/RE

3, there is difference between DVD-RAM and BD-R/RE about spare area?

 

thanks in advance.