Hi ejenkins4299,
Thanks for posting in Apple Communities.
To be clear, is iPhone lagging in performance only while using CarPlay? Does this affect specific apps?
Make sure that your iPhone and your car are running the latest updates. You may need to refer to the car manual to update the firmware. If the issue occurs only with apps on iPhone, restart iPhone, close the app and reopen, install any app updates, and delete and download the affected apps.
You can find these steps in If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open.
Check that iPhone isn't on Low Power Mode. This reduces how much battery is used and some tasks can take longer. Ensure that you have iPhone working in an acceptable temperature. Being placed directly in sunlight or in front of an air conditioning vent can cause performance differences.
Find these steps and additional information in About iOS or iPadOS performance on your iPhone, iPad, or iPod touch.
Regards.