How do you improve the performance of your app

Question

for an example I'm creating a game for PC how do I improve its performance via code in any c languages like c c++ and c#

Answer 1

Link some of your code, way too broad of a question

Answer 2

Look over the code which takes much memory or execution time or which is executed often. What happens at the lowest level you can think of? How could you improve it?

Answer 3

big O notation is one way. I just learned about it last month. And ive been in the industry for 4yrs😭