Drive slowing down to 1x reading

vbimport

#1

Is this acceptable? That sometimes benq 1620 drive will slow down nearly 1x read making it near 50mins to read in retail disc to HD? Again is Universal Columbia Box sets that are doing this. Like Dukes of Hazzard Season Two, Disc 4 of Columbo Season Two will not read first vob. The rest of columbo and pretender as I stated above reads in really slow.