Well, it probably isn't another 13GB, but I've been trying my best to open GW2 and keep it up to date for the BWEs. Just opened today with the next beta event starting in less than 2 hours and was greeted with over 85,000 files to download. My internet has been hardcore shitting the bed recently so this is gunna take me some serious time to download.
Just a warning to everyone who plans on playing tonight, make sure you're up to date. I'm at 50MB at the moment and still not even 1% done. So this thing is over 5GB :(
EDIT: Reached 1% at 72MB, so a very rough estimate puts this at over 7GB. FUUUUUUUUUUUUUUUUUUUUUUUU
EDITEDIT: People are saying it's 5GB.