1. Restart your phone
It sounds obvious, but it's the step that fixes slowness accumulated from continued use the fastest. Over the days, your phone stores processes and app leftovers in memory that you no longer need, and a simple restart clears them completely. If you haven't turned it off in several days, try this before anything else.
2. Close apps you're not using in the background
Many apps stay active even when you're not using them, checking notifications or updating data. Open your phone's recent apps menu and close the ones you don't need right now. You don't need to close them all every time, but if you notice your phone slows down right after using several apps at once, this step usually helps immediately.
3. Uninstall apps you no longer use
Every installed app consumes resources even if you don't open it: background processes, notifications, data syncing. Go to Settings → Apps and check which ones you haven't opened in months. Uninstalling the ones you don't use frees up memory and reduces the overall load on the system, plus storage space.
4. Update the operating system
Android and iOS updates don't just bring new features: they usually include performance improvements and bug fixes that directly affect your phone's speed. Check under Settings → Software update to see if there's a pending version and install it, preferably while the phone is charging and connected to wifi.
5. Turn off animations and visual effects if your phone is a few years old
On older models, app opening and closing animations can create a feeling of slowness even when the system is responding well. On Android you can reduce or disable them from developer options: go to Settings → About phone and tap "Build number" several times until developer mode is enabled, then go to Settings → Developer options and reduce "Window animation scale", "Transition animation scale" and "Animator duration scale" to 0.5x or turn them off.
6. Check for a malicious or oddly-behaving app
If your phone suddenly slows down, heats up for no apparent reason, or the battery drains much faster than normal, an app might be consuming resources in the background without you knowing. Check Settings → Battery to see which apps consume the most, and be wary of any you don't recognize or that you installed outside the official store. Uninstalling them usually solves the problem.
7. When to consider that your phone has reached the end of its useful life
If your phone is more than 4-5 years old and no longer receives security updates from the manufacturer, it's normal for it to show its age against increasingly demanding apps. In that case, no matter how many of these tricks you apply, the improvement will be limited. It's a good time to consider a replacement, especially if the battery has also degraded or storage has become too tight.