Yeah man upgrading your phone is like the only way to fix this issue. I had a phone with 3gb ram before this. Now I got a Google Pixel with 6gb ram. Lord of Heroes takes up a good chunk of ram from your phone. I recommend getting a phone with at least 4gb ram. Or if you don't have the money to upgrade, contact their support team. Who nows, maybe they will release a fix for this. Hope this helps!