Yep. I can confirm that. Even on an overclocked i7 6700k, it took 3-4 hours. And yeah, you'll need to dig a long tunnel. It's a creative map so get some tools and torches from the inventory.
Great looking map, great idea, great hard work. Thank you!
You can get the WZZIP tool here: http://www.winzip.com/win/en/prodpagecl.html
It does not come with the standard WinZip.