I have the same problem. iPhone 5 freezes to a white screen when I try and access Contacts then after about 20 seconds it goes back to the phone. This began occurring after the IOS 10 update
I use a Microsoft Live account for my emails and Outlook (not the online version) for email, calendar and contacts.
After many hours of I narrowed it down to my Microsoft Office Contacts or “People” as they call it.
If I go to my phone settings and select the Outlook account to manage my contacts it freezes. When I turn off the option to my outlook account it works fine.