Hello Bearod,
We're glad you thought to ask Apple Support Communities about the issue you're having with your iPhone becoming unresponsive. When your iPhone stops responding you can force restart it to see if you can regain control, instead of letting the battery drain. Here's how: Force restart iPhone
For the performance issue with it not responding, the steps in the following guide should help: About iOS performance on your iPhone, iPad, or iPod touch
You'll also want to be sure that your iPhone is updated. The current software version is iOS 14.4. To see what you have installed tap Settings > General > About. If an update is needed, be sure to back up your iPhone first:
How to back up your iPhone, iPad, and iPod touch
Update your iPhone, iPad, or iPod touch
How to manually update apps on your Apple device
Let us know how it goes.
Take care.