funny that I should come across your posting almost instantly I also own two LG drives and have been experincing some problems and as it were I was coming on this board to look for some answers.
anyhow, back to your issue. I've searched a few sites (not this one yet as I was just in the process of doing this) but from what I have read this problem is due to poor production from LG CHINA. When I find the original post about this issue I will put link it, but anyhow the short answer is that the tolerance for jitter on these drives that came from china suck. So when the drives spin up to higher speeds there are errors on the cds so it spins back down to a lower burning speed, effectivly slowing down your whole burn process.
I suspect that if you take a look, 1st) on the sticker of the drive you will notice made in china (ok I keep on saying this because apparently if you got drives made from LG KOREA its not a problem) and 2nd) if you go to www.cdspeed2000.com
and run scandisc on your burned cds you'll prob. notice some errors.
As for me my two drives are 8481B and 8525B, got the 8525B to test to see if this problem also affected this drive, and yes it does. So this one is going back and I'm not touching LG drives again.
on the 8481B with 24x CDRW >90% errors on scandisc
on the 8525B with 24x CDRW >10% errors on scandisc
on the 8481B with 42x CDR no errors with scandisc but burned programs will not install! (CRC error during the installation process)
however it does take almost 4mins to burn 700MB CDR at 42x
going to waste more cdrs to test the 8525 now.
So my suggestion to you matt is, if you can switch the drives for a Liteon if you can.