Without knowing what profile you used (Data CD? Game CD? Protected PC Game? or user-defined?) it’s difficult to say what goes wrong (or even if anything goes wrong). The CD used is another factor, of course. Perhaps even the drive.
Some time ago, I tried to copy a CD into a forensic case: there were bad sector on the medium, towards the end, and that caused the drive to re-read those sectors for something like 100 attempts before it decided that ‘yes, this sector is bad’, and returned. Of course, the forensic acquiry program immediately ordered another try, which mean that the copy stuck for more than 2 hours on those bad sectors before I terminated it, and it made very little progress after the first 10 minutes.
The same CD, copied with CloneCD, with a user-defined ‘Forensic copy’ profile, saying: Fast Error Skip Setting: Automatic, Intelligent Bad Sector Scanner checked, and 1 Sector Skip was finished after 4 minutes. The bad sectors were indicated as bad, but it didn’t take ages to come to the conclusion that they were bad. (Don’t recall if I configured hardware or software correction – that is a reader setting, not a profile setting). I may have lost good data with that 1 sector skip, but I figured that it was unlikely. (Even so, I was ahead of that forensic program which skipped 64 sectors on a read error.)
Furthermore, a log file somewhere showed that CloneCD reconfigured the error behaviour of the drive: from those 100+ attempts to something like 1 or 2, which seemed to explain the speed.
Of course, my requirements may be lower than yours: the difference between 2 hours unfinished job and 4 minutes finished and knowledge about what sectors were bad was enough for me.