Need help understanding anomalies in read speed

[qanda]This thread is about the LG GGCH20L Super Multi Blue Blu-ray Disc and HD DVD-Rom Drive. Click here to see full specs[/qanda]I have an LG GGC-H20L Blu-ray combo drive. I used MCSE to flash the 1.03 FW version with an “increase speed” version and I have to admit that for most discs it reads about 50% faster.

My issue is the following:

I am transferring all my DVDs to the hard drive on this machine using this DVD drive. It’s a Vista Media Center machine (SP1) with plenty of storage so I’m not compressing any of the DVDs. They’re all being copied at 100% size. Before the FW update I was getting somewhere around 5-7 MB/s transfer using DVD Fab v6.0.1.0.

After the update I’m getting varying speeds depending on the size of the DVD.

For an 8,042MB DVD I got a maximum of 10.3MB/s transfer (around 10x). But for smaller DVDs (around 5-6 GB) I got a blazing 17.5 MB/s (close to the advertised 16x for the drive).

So my questions are: Is this normal? Am I going to get different read rates on different size DVDs? Is there anything I can do to get 17+ MB/s speeds on larger DVDs (7GB+)?