Why is my writer getting progressivley slower?

[allbouthepot]

I'm using two different optorite writers. I had been using the dd0405 for about 500 cd burns and 500 dvd burns. It started giving me an occasional skip in the disc so I began using the other writer I have. IT is a DD0106. It is a dual layer but I use normal dvd-r's. My burns at 4X used to take about 23 minutes and all of a sudden the time it takes to burn has doubled? What am I doing wrong?
Nero cdspeed is greek to me, I have no idea what condition my burner (laser ) is in. How do I know when I need a new one?
I believe I have a buffer problem because I was having a large nu,ber of unsuccessful burns, so I started to reboot after every burn and started getting a good success rate
Thanks for any or all answers

Also, I use only top rated media (real TY or Ritek) and burn at 4x or 8x

[unclebud]

Defraging the hard drive might help but burners don't last forever. Iv'e burnt out 3 CD and DVD burners in the last 8 years. Luckly they are very cheap now compared to 5-8 years ago.