> I wonder if it's possible to save all files in cache
> but without saving its content data. Im figuring out that if I
> specify "-k", I will need double room to save, on
> the one hand, the site structure with its corresponding
> files and, on the other hand, the content of all those files
> (compressed) inside "new.zip" (and this size is even greater 
> because if I try to update, I will have to add size(old.zip)!)

You can turn off the cache completely if you don't need to update the project. 
Or you can delete old.zip when you have finished an update.