Why is this happening Please help

I seem to be able to burn a movie that is like 2 hours in about 30 minutes and then put in a moive that is like 1 hr 36 minutes and take 45 minutes. What gives is this normal. Also should total remove clonedvd2 ver.2.4 before going to ver.2.5. Thanks for the help :confused:

you should check DMA setting first