Hey rexsard,
We'd recommend reviewing the information in this article as it provides steps that can help resolve performance issues on iPhone: If your iPhone or iPad is running slow - Apple Support
"Look at your battery health
All rechargeable batteries are consumable components that become less effective as they chemically age. Over time, the rechargeable batteries in all iPhone and iPad models will diminish in their capacity and peak performance and will eventually need to be replaced. iOS can show show battery health and recommend if an iPhone battery needs to be replaced. Go to Settings > Battery and tap Battery Health. Battery Health is available only on iPhone.
Check your iPhone battery >"
We'd also suggest the steps here as they can help resolve issues with apps not responding: If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open - Apple Support
Regarding the issue with receiving images in Messages, you may want to provide some additional information about that.
What happens when you try to view the image? Is this happening with images from only one contact or multiple contacts?
Thanks!