If Disney Plus is lagging or crashing, clearing the cache is the first thing you should do.
For Firestick: Settings -> Applications -> Manage Installed Applications -> Disney+ -> Clear Cache.
For Roku: There is no “Clear Cache” button, so you must uninstall the app, restart the Roku, and reinstall it.
For Samsung TV: Settings -> Support -> Device Care -> Manage Storage -> Disney+ -> View Details -> Clear Cache.