Hello Akisiphone,
Welcome to Apple Support Communities!If we understand your post correctly, while playing a game on your iPhone the phone seems to throttle and get hot. We'd like to help!
Your device might get warmYou might notice that your device feels warmer when you:Set up your device the first timeRestore from a backupWirelessly charge your deviceUse graphics-intensive or processor-intensive apps, games, or features, including augmented-reality appsStream high-quality videoThese conditions are normal, and your device will return to a regular temperature when the process is complete or when you finish your activity. If your device doesn't display a temperature warning, you can keep using your device.
If your device gets too warmiOS and iPadOS devices have built-in protections to prevent overheating. If the interior temperature of your device exceeds the normal operating range, your device will protect its internal components by attempting to regulate its temperature. Here are some of the higher ambient-temperature conditions and activities to avoid, because they might cause your device to change performance and behavior:Avoid leaving your device in a car on a hot day.Avoid leaving your device in direct sunlight for an extended period of time.Avoid using certain features in hot conditions or direct sunlight for an extended period of time, such as GPS tracking or navigation in a car, playing a graphics-intensive game, or using augmented-reality apps.If the interior temperature of your device exceeds the normal operating range, you might notice these changes:Charging, including wireless charging, slows or stops.The display dims or goes black.Cellular radios enter a low-power state. The signal might weaken during this time.The camera flash is temporarily disabled.Performance slows with graphics-intensive or augmented-reality apps or features.Additionally, if you're navigating, your device might show this alert and turn off the display: "Temperature: iPhone needs to cool down." Navigation still provides audible turn-by-turn directions. When approaching a turn, the display will illuminate to guide you through the turn.If your iPhone, iPad, or iPod touch gets too hot or too coldIf you are experiencing a different temperature than what is in the article let us know.
For the frame drop while playing a game, do you have a good Wi-Fi and or cellular connection?Does this only happen in the one game or others?
Have you tried to contact the app developers of the game to see if they have any tips to make the game run better? How to contact an app developer
Thank you for using Apple Support Communities. Take care!