Performance Optimization Techniques

What performance concept is demonstrated by this optimization?
// Before optimization
function processData(data) {
  return data.filter(x => x > 0)
           .map(x => x * 2)
           .reduce((a, b) => a + b, 0);
}

// After optimization
function processDataOptimized(data) {
  let sum = 0;
  for (let i = 0; i < data.length; i++) {
    if (data[i] > 0) {
      sum += data[i] * 2;
    }
  }
  return sum;
}
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