DVD Read and Burn Speed of Superdrive Slow

I've got a new iMac and this is a possible hardware or Bootcamp question. I use DVD Fab on the Windows partition of my new iMac to burn DVDs. This iMac and the other one I own are not very impressive on their read/write speeds. I have this new iMac loaded up with RAM, 3.4 GHz i7, etc. and I'm seeing read/write rates of 3x to 4.5x at best. It only hits the higher speed around 4 or above after it hits it stride about 3-4 minutes into the read or write of the DVD. In other words it starts out very slow 1.2x or so and creeps up to the higher speed only to be done with the project shortly after. So the average read/write rate is much lower. I have a Windows PC that I built about 4 years ago with a dual core AMD chip, 8 GB RAM and a decent 512 MB Nvidia card with a Sony ide optical drive that shames these iMacs using the same DVD Fab software. I can read and burn a DVD in about 50% of the time it takes on either of my iMacs.

Any ideas? I'm guessing that the word Superdrive is an overstatement. Apple still uses and ide optical drive when SATA optical drives have been out for some time. However in the above example all computers were using ide optical drives. Thanks.