Re: After OTA upgrade, My Samsung A5's Contacts is getting hanged every time
Welcome to Android Central! Are all of your contacts synced with Google, or are a lot of them saved on the local Phone account? If they're all synced with Google, then go to the App Manager, select Contacts and Contact Storage, and Clear Cache/Clear Data, then Force Stop them. Now open Contacts again and give it a few seconds to sync with your Google account again. Does that help?
Don't do this if you have contacts saved to the local Phone account, though, because it will erase those contacts. In generaly, I would strongly recommend keeping your contacts in your Google account anyway, since they're safe there in case something happens to your phone.