importing from iphoto requires a lot of disk space

Hi,

I just purchased Aperture and am in the process of importing my iPhoto library. I followed Apple's video suggestion but was concerned as I started doing it on my own computer.

I was going to import from Iphoto and leave the files in the same location. But I immediately got a warning that this would take up 9gb of space.

1. is that permanent or just requiring 9gb while the import takes place?
2. if I'm using the iPhoto library and am leaving them there, why is it going to cost me so much disk space? (my laptop is limited on space, hence my concern
3. Am I better off doing a 1-time import to a new location and deleting the iphoto library - yes I already backed up (I'll be using Aperture here on out)?

thanks!