Disc space

When I used InCD I didn’t have any problem with disc space. I’m trying out Nero Express using multisession and noticed that everytime I add new data to the cd-rw I’m using a lot of disc space. I had 4 small folders on my disc and it reads 80 mbs. The way it’s going I’ll be out of space in no time. What is using all this disc space? Should I go back to InCD?