Diagnosis
The TV's internal storage or memory is likely clogged up. As you use apps, they cache data, and over time this can slow the processor (Tizen OS) to a crawl, causing freezes and crashes.
How to Fix It
You need to clear the cache and potentially reset the Smart Hub. First, for a quick clean, go to Settings > Support > Device Care. Run 'Memory Booster' and then 'Manage Storage'. Here, you can see which apps are using the most space. Clear the cache for the problematic apps (like Netflix, Disney+). If that's not enough, do a full Smart Hub reset. Go to Settings > General & Privacy > Reset. Select 'Reset Smart Hub'. This will not delete your installed apps, but it will log you out of all of them and clear all the cached data. You'll have to sign back in, but performance will often snap back.
If That Didn't Work
The ultimate step is a full factory data reset from the same menu. Be warned: this erases all your settings, accounts, and installed apps, returning the TV to out-of-the-box state. Only do this if the slowdown is unbearable. Before you do, note down your picture settings so you can re-enter them.
Heads Up
Avoid leaving apps running in the background. Get in the habit of pressing the Back button until you exit an app completely, rather than just pressing Home. An app left running is using RAM and can cause conflicts.