My game is running really slow. How do i make it run smooth and fast?

Right now things fall really slow and i would really want my game to be fast-paced action.

https://www.roblox.com/games/2773581932/Last-One-Running

What is causing it and what do i do to solve it?

Also i have tried to fix those while true do wait(0.1) -- big function end

into event triggered ones.

My game is quite small yet other games like phantom forces and jailbreak get to run really smoothly. How do they do it?

It could be that you are using too many parts, objects, or items in your game. Try to simplify those. Also try to use shorter and better scripts. And to tell you the truth, I don't even know what you are talking about when you say the game is too slow. It works fine for me. Maybe your computer is just poor quality?