Audio cd ripping speed very slow WD 1640

I was creating an image file from an audio cd with the 1640 using clonecd , and when it first starts it is at 4x, then slowly increases to around 8.5x before it finishes. I’ve got firmware bskb. Not sure what more info needed, but just curious as this seems pretty slow, since my lite-on hd-166S ripped it in 1/4 the time or so, topping out at 33x.