Performance Optimization Techniques

What performance improvement technique is demonstrated in this code?

const expensiveComputation = (() => {
  let result;
  let calculated = false;
  
  return () => {
    if (!calculated) {
      console.log('Performing expensive calculation...');
      result = Array(1000000).fill(0).map((_, i) => i).reduce((sum, val) => sum + val, 0);
      calculated = true;
    }
    return result;
  };
})();

Function inlining
Lazy initialization
This code demonstrates lazy initialization (also known as lazy loading or lazy evaluation), a performance optimization technique where computation or initialization of a value is deferred until it's actually needed. In this example, the expensive calculation is only performed on the first call to the function; subsequent calls simply return the cached result. This is particularly valuable when: 1) The computation is expensive, 2) The result might never be needed in some program executions, 3) There's a significant delay before the value is first needed. Lazy initialization reduces initial load time and saves resources, particularly for expensive operations that may not be needed immediately or at all.
Virtual DOM diffing
Web worker offloading

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