I've heard complaints, and seen first hand when testing in a virtual machine, that Windows is very slow unzipping releases. Especially my custom ones due to their very large size.
Here are some things you can do to speed this up:
1. Trash Windoze's built in zip utilities by installing 7zip so that it overrides everything. It is much much faster and supports more archive types.
2. Don't do anything else while it is unzipping. Anything else that accesses the disk will slow the unzipping down.
3. If it's gonna take 5 minutes (for 7zip, my latest MHQ took 17 to unzip in my VM using the Windoze built in crap) get up and do something away from the computer like get a snack, take a piss, etc... this helps with #2 because you're away from temptation.
4. Finally, if you've done all of the above, you'll either have to deal with any further slowness or switch to Linux. On my laptop running Fedora Linux 20 with around 30-50 other things open and me doing other things the latest MHQ takes < 3min to unzip.
EDIT: Do not use WinZip instead of 7zip. For one, WinZip is paid and 7zip is free. For another, WinZip is (lately) almost as slow as Winblows' built in compression utils.