Posted on Jun 25

Animation vs Transition: Which one will kill your performance first? 🔥

🔥 CSS `animation` vs `transition`: Which one performs better?

Every front-end developer has faced this dilemma at least once:

Should you use animation or transition?

The common wisdom says transition is faster—but is that really true?

And does that apply to all CSS properties?

Let’s find out.

🧪 Performance testing at scale

To uncover the truth, we built a stress-test environment with 2,500+ animated elements and tracked a wide range of performance metrics:

✅ Average and lowest FPS
⏱️ Frame delay (delta) and max spike
💾 JavaScript heap usage
📈 Peak memory consumption
🧮 Total allocated memory
🕐 Total task duration

📊 The most telling metric?

How long does it take for the animation to complete fully — that’s our benchmark.

👉 Try the live test environment

⚙️ How we measured

To ensure objective results, our setup:

Renders thousands of elements on the screen
Waits briefly before starting the animation/transition
Captures performance metrics on every animation frame

What we tracked:

🎯 Average & lowest FPS
⏳ Frame delay (delta) and its peak
🧠 JavaScript memory usage
🔥 Peak memory during animation
⌛ Full duration of the animation

This helped us understand how CSS animations behave under load—not just in theory, but in real browsers.

😱 What we found

You might think modern browsers can handle thousands of animations.

Spoiler: They can’t.

Just ~2,000 animated blocks are enough to cause visible frame drops and lag.

Here’s a snapshot of the test: hundreds of blocks animating in the background, while performance metrics are tracked live in the center of the screen.