CSS と JavaScript のアニメーションのパフォーマンス

const boxes = [];
const button = document.getElementById("toggle-button");
const boxContainer = document.getElementById("box-container");
const animationType = document.getElementById("type");

// ボックスの作成
for (let i = 0; i < 1000; i++) {
  const div = document.createElement("div");
  div.classList.add("css-animation");
  div.classList.add("box");
  boxContainer.appendChild(div);
  boxes.push(div.style);
}

let toggleStatus = true;
let rafId;
button.addEventListener("click", () => {
  if (toggleStatus) {
    animationType.textContent = " requestAnimationFrame";
    for (const child of boxContainer.children) {
      child.classList.remove("css-animation");
    }
    rafId = window.requestAnimationFrame(animate);
  } else {
    window.cancelAnimationFrame(rafId);
    animationType.textContent = " CSS アニメーション";
    for (const child of boxContainer.children) {
      child.classList.add("css-animation");
    }
  }
  toggleStatus = !toggleStatus;
});

const duration = 6000;
const translateX = 500;
const rotate = 360;
const scale = 1.4 - 0.6;
let start;
function animate(time) {
  if (!start) {
    start = time;
    rafId = window.requestAnimationFrame(animate);
    return;
  }

  const progress = (time - start) / duration;
  if (progress < 2) {
    let x = progress * translateX;
    let transform;
    if (progress >= 1) {
      x = (2 - progress) * translateX;
      transform = `translateX(${x}px) rotate(${
        (2 - progress) * rotate
      }deg) scale(${0.6 + (2 - progress) * scale})`;
    } else {
      transform = `translateX(${x}px) rotate(${progress * rotate}deg) scale(${
        0.6 + progress * scale
      })`;
    }

    for (const box of boxes) {
      box.transform = transform;
    }
  } else {
    start = null;
  }
  rafId = window.requestAnimationFrame(animate);
}

<div id="header">
  <button id="toggle-button">切り替え</button>
  <span id="type">CSS アニメーション</span>
</div>
<div id="box-container"></div>

#header {
  position: sticky;
  top: 0.5rem;
  margin: 0 0.5rem;
  z-index: 100;
  background-color: lightgreen;
}

#box-container {
  margin-top: 1.5rem;
  display: grid;
  grid-template-columns: repeat(40, 1fr);
  gap: 15px;
}

.box {
  width: 30px;
  height: 30px;
  background-color: red;
}

.css-animation {
  animation: animate 6s linear 0s infinite alternate;
}

@keyframes animate {
  0% {
    transform: translateX(0) rotate(0deg) scale(0.6);
  }
  100% {
    transform: translateX(500px) rotate(360deg) scale(1.4);
  }
}