Is this an optimal java reflection helper?

I have made this reflection handeler/helper. And I made it because everyone is talking about how reflection is resource intense when searching for functions or variables. And I am asking you if it is effective at partially removing the resource intensity or if you have any tips! I mad a short description so you don't need to look into code to much!

Description:

I have 2 lists that contain functions and variables that have been used. And if a getFunction is called again with the same function that needs to be returned than it will pick it up and return the function from the list and by that avoiding to search for the same function again! It is basically saving methods and returning them when needed! :)