So, I accidentally forgot to set max speed when burning DVD. Thanks to Taiyo Yuden Blank DVD Media and SONY DRW-830A, ImgBurn smartly set the burning speed to 18x.

And it never actually reach that speed –

I 23:13:25 Average Write Rate: 15.426 KB/s (11.1x) – Maximum Write Rate: 23.131 KB/s (16.7x)

Yeah – 15 MB/s average and 22 MB/s maximum. The harddisk is also reaching its limit. I wonder how will the speed be if I tried to burn a 4.7×10⁹ bytes data… (this one is 3.55 GB)