Lightroom library is almost 5gb after importing photos

Question

I am new to Lightroom 5 and just imported about 4000 photographs.  I just added them to Lightroom since they were already on my hard drive.  I was amazed an confused why the Lightroom library file is almost 5 gb.  I have yet to do anything else except import.  I didn't think the library file would start to get large until I started processing and editing the files.  What can I do to not have my library file get so huge, or is this what I can expect with Lightroom?

Answer 1

Minimal means a thumbnail-sized preview, so anything larger than that would be recomputed at the time you first view the photo.  If you feel you'll be scrolling through all 4000 photos in Library Grid view at some point then compute Minimal previews. 
I'd compute standard monitor-sized previews the first time you import a new folder of photos so you can do your tagging and flagging and rating and rejecting using the Fit or Fill zoom levels without waiting too long.  If you find yourself needing to zoom in to check focus on many of the images then maybe computer 1:1 previews for the newly imported folder, otherwise zooming into 1:1 will require a preview to be computed rather than looked up from the previews folder.
Once you go to Develop the previews aren't used except as a placeholder until the on-the-fly rendering has occurred as you zoom in or out or flip to the next image in Develop.
You'll figure out what you want to do after working on a few folders of images, the tradeoff between getting started on any of the photos in the folder vs waiting longer as you move to each one for the first time.