Being Tricky
The short answer
Restart the phone, install system and app updates, keep at least 10% of storage free, and remove apps you don't use. On a Galaxy, run Device care.
At a glance
About 20 minutes · Easy · For Android
Key point 1 of 5
Google says Android phones can start having problems when less than 10% of storage is free, so storage is the first thing to check.
Key point 2 of 5
A restart and pending system and app updates fix many slowdowns, and both are free.
Key point 3 of 5
Cleaner and booster apps repeat what Android and Samsung's Device care already do, and cleared cache builds back up over time.
Key point 4 of 5
Clear an app's cache for a single slow app, and clear its data only if you accept losing its settings and sign-ins.
Key point 5 of 5
A factory reset is the last resort; back up first, because it removes every app and its data.
You might ask
Does closing apps from the Recents screen speed up my phone? Not by much.
Want every step?
Being Tricky