You can try testing your device in safe mode to see if you still experience the same symptoms.
This step will temporarily disable all your third-party apps, but none of your personal data will be deleted. Your customization settings (Wallpaper, Themes, et cetera) will be reset to default once you exit this mode.
Please follow the steps below:
1. Turn the device off.
2. Press and hold the Power key past the model name screen.
3. When "SAMSUNG" appears on the screen, release the Power key.
4. Immediately after releasing the Power key, press and hold the Volume down key.
5. Continue to hold the Volume down key until the device finishes restarting.
6. Safe mode will display in the bottom left corner of the screen.
7. Release the Volume down key when you see Safe Mode.
8. To exit Safe Mode, restart your device.
For your text message concerns, you will need to contact your carrier regarding that.
If you still experience the slow and sluggish symptom in safe mode, I would recommend fully backing up the device and perform a factory reset. I know this may not be the ideal step you want to take but this will reset the device to its factory settings.
Note: If the symptoms do not occur in safe mode, then there may be a third-party app that can be causing this to occur. I would delete each individual third-party app until the symptoms stop.
You also have an option to visit a UBreakIFix for a technician to evaluate your device.
