Diagnosis
Not broken. The built-in storage is nearly full from app cache and updates. The processor bogs down.
How to Fix It
Go to All Settings > General > System > Storage. Check used space. Select 'Delete Viewing History' and 'Delete Voice Recognition Information'. Then go to All Settings > Support > Device Care > Optimize Now. Run it.
If That Didn't Work
Perform a soft reset. Unplug the TV from the wall for 60 seconds. Plug it back in. This clears the system memory.
Heads Up
Do not do a factory reset unless necessary. You will lose all logins and settings. The storage will fill up again in a few months. Repeat the cleanup.