To max out KE you would have to shoot what most would consider a light arrow.
Not true , a heavier arrow will soak up more energy while on the string and carry it with it further than a light arrow .
What is the best way to get kinetic energy
Increase draw weight , decrease brace height , get all the junk off of your string , and use a heaver arrow . Those are the easy est ways , making sure your bow is tuned , using a narrower string that has the correct amount of twists , or x-coat to prevent ballooning , lubing axles and various others will give less dramatic returns .
edit - longer draw will do it to , but your draw "is what it is" so its not an option .