Diagnosis
The built-in smart TV platform can run out of memory or get bogged down by cached data from the apps. It's a common complaint on this model after a few months of use.
How to Fix It
You need to clear the cache for the problematic apps. From the home screen, go to Settings > Device Preferences > Apps. Find the app that's freezing (like Netflix). Select it, then choose 'Clear cache'. Do NOT select 'Clear data' unless you're okay with logging back in. After clearing the cache, force stop the app from that same menu. Then restart the TV by holding the power button on the remote and selecting restart.
If That Didn't Work
The TV's internal storage might be critically full. Go to Settings > Device Preferences > Storage and see what's using space. If it's mostly 'System' or 'Cached data', a factory reset (from the same menu) will wipe it clean, but you'll have to log into everything again.
Heads Up
These TVs don't get major Android/Google TV updates forever. If your apps are becoming unsupported, you might need to add an external streaming stick (like a Roku or Fire Stick) to the HDMI port for better performance.