Hi, dawny_henny.
Welcome to the Apple Support Communities. We’re glad you decided to reach out about the issues you’re experiencing with your iPhone after updating. If we understand correctly, not only are your recently added contacts not appearing, but it sounds like the Messages app is also becoming unresponsive and impacting your entire device.
We suggest starting with the following steps:
Update to the latest iOS version:
Update your iPhone, iPad, or iPod touch - Apple Support
Check to see if there is a lack of available storage that may be impacting the performance on your iPhone.
How to check the storage on your iPhone, iPad, and iPod touch - Apple Support
Finally, check your battery health to see if it could be an issue.
iPhone Battery and Performance
If the issue remains unresolved, we’d like to learn more.
- Is this happening with the iPhone 8 listed in your profile? If it is, which iOS version is installed?
- Are you using iCloud to sync your Contacts and/or Messages? If so, do you notice any other issues with iCloud content? (e.g. Photos, Calendars, etc.)
- Are you using Wi-Fi or a cellular data connection? Have you tried both?
All our best.
