WhatsApp is stuck at initialzing
Yeah the 4170 contacts is the thing because of which it's taking so long. What I'd suggest is, try removing your Google Account(after syncing everything ofcourse) so that contacts are removed and THEN try starting WhatsApp.

Enter your number with no contacts and let it initialize. That should fix the problem. After WhatsApp is running just log into your account and resync contacts to phone and WhatsApp.