Hey there leobaron,
Thanks for reaching out to the Apple Support Communities.
To get started, if you're noticing performance issues with your iPhone, give the steps listed in the following resource a try that can help: If your iPhone or iPad is running slow - Apple Support
If still having issues after going through the steps above, what specific animations are you noticing issues with? Are these animations in a particular app, or when scrolling on your Home/Lock Screen?
As for the issue you mentioned about your iPhone getting warmer than expected, does this happen when charging your iPhone or when using a particular app? For more details, and steps that can help with that issue, check out this next link here: If your iPhone or iPad gets too hot or too cold - Apple Support
We hope that's able to help.
Best regards.