iOS is much better optimized than Android, so usually only clearing a bit of memory, restarting, and ending background apps and processes will stop lag on iOS.
Keep in mind that it's not always the OS that's the problem. War Robots is a semi resource intensive game, it requires quite a bit of RAM to run it. A shortage of RAM space could be the cause of lag.
- The built-in battery saver for Android works by severely limiting processing power. Turning battery optimization off just for WWR is another option (Settings > Battery > Battery Optimization > All Apps > WWR > Don't Optimize).
- A stock phone has many services and apps constantly searching for nearby phones, your GPS, Bluetooth, and even printers. Every phone has at least 3 constant printer services that constantly search for printers. You can disable a many of these active services and apps that you don't use.
- Try not to play the game when it's charging, it will heat your phone enough that your phone's CPU will cut its power in half, severely crippling your FPS, to stop you from melting your components.
- Try to find a well-lit room to view your screen, so you can turn the brightness as far down as you can while still maintaining a playable/fun experience. Your phone uses a lot of its power on brightness alone, cutting that gives a small fps boost and longer gaming. If your device has a very reflective screen, it is better to play in a dimly lit room, as there is not much light for your device's screen to reflect.
- Game Tuner reduces gameplay resolution and increases fps, even without rooting.
- Close background applications. Or if you want to force close it, you can tap and hold an app then drag it to app info, from there, click “Force Stop”.
- Heavy duty connection apps such as FB Messenger, Spotify, etc. can reduce performance. Even with the apps not running in the foreground, they all have services which constantly run in the background. If you're not using them (or don't need them for the moment), you can refer to #6 and close them. To start them again, just open the app.
- Enable Developer Options and enable Force GPU Rendering.
Disable Google Play Store. Disable pre-installed apps such as Audible, anything having to do with Amazon, NewsRepublic, and Google Play Music, Google Play Newsstand, Google Play Books, etc. EXCEPT Google Play Games which is needed to run the app. DO NOT TOUCH ANYTHING TO DO WITH THE SYSTEM.
Uninstall updates to Google Play Games. Uninstall updates to Google Play Services. Unless you're on Kit Kat (Android 4.4), go into App Manager (Lollipop) or Running Services (Marshmallow) and kill ANYTHING with a “Stop” button. Don't worry, most of it will restart again shortly, but with a lower RAM usage.
Disable Google Chrome browser if pre-installed. Install Chrome Beta or Chrome Dev in its place so you can run it through the Greenify.
- Clear out apps, videos, and photos that you do not use.
- Try to find a well-lit room to view your screen, so you can turn the brightness as far down as you can while still maintaining a playable/fun experience. Your phone uses a lot of its power on brightness alone, cutting that gives a small fps boost and longer gaming.
- Clear browsing data and history from any browser apps. Clear your reading list and bookmarks. Close all tabs.
- If iOS is not up to date, update it.
- Close background apps (double press home button).
- Close background processes(hold the power button until reset message appears and then hold the home button until the reset message disappears).
- Reset your iPad/iPhone.