if you build too many things the world will lag, hitting mobs is very hard as you must wait before hitting it again, or is theres too many mobs. in my friends world, we had a river full with tropical fish seperating our countries (this was on a flat world), the fish caused lag, she \kill @ed everything. i then added some ice and snow and its not laggy anymore. but i built a city and its really lagg. please make a way to see FPS on Bedrock and not just Java.