Why fewer and fewer developers use physics engines for web animations

What happened

While developing Stress Release, an interactive digital "squeeze toy" for stress relief, agency Isadora did something that goes against the industry reflex. Instead of reaching for a physics engine like Matter.js or Cannon.js, the typical choice for "squishy," bouncy, deformable interactions, they built the entire experience without a single line of WebGL code. The solution was a combination of programmatically controlled Lottie animations, DOM manipulation, and math based on the distance between a click and the center of the character.

Why does this matter? Because it reveals something that gets forgotten far too often in web development: more "advanced" technology isn't always the better choice. Physics engines create plausible movement, but the animators on this project needed deliberate, precisely defined movement instead. Once the team at Isadora realized this, they simply dropped the physics engine and achieved a better, more controlled result with a simpler tool.

Background: why they dropped the physics engine

For the Stress Release project, the core requirement was complete, deterministic control over the animation. The animators prepared precise .json Lottie files where, for example, the "mega squeeze" reaction required exactly 181 frames of build-up followed by a specific release sequence. A physics engine would have overwritten these hand-crafted keyframes with algorithmic approximations, destroying the animators' precise work.

The solution was programmatic state control through the Lottie API. Every user click was converted into local coordinates on the character, and the distance from the center (calculated using the Pythagorean theorem) determined everything: the number of points, the intensity of the reaction, and the location of the burst animation. The system worked like a target, with concentric rings around the character's center, where the visual complexity of the Lottie SVG had no effect on hit detection, since the click area was always a simple circle.

On top of that, the entire experience was made responsive purely through CSS variables, recalculated every time the window was resized. This let the Lottie animations naturally adapt to different devices without losing their state, which is far simpler than recalculating bounding boxes and collision vectors the way physics engines require.

What this means for Slovenian small and medium businesses

You're probably wondering what a stress-relief squeeze toy has to do with your website for a carpentry shop, a dental practice, or a furniture store. The answer is simple: it's about the principle, not the specific example. Any business owner who has ever ordered a "modern, interactive" website has likely run into a developer who suggests the most technically demanding solution simply because it's trendy. The result is often slow, unstable websites that run poorly on mobile phones, drain battery faster, and turn users away before they even see what you offer.

This example from the world of game development clearly shows that experienced developers prefer a simpler, more controllable tool whenever it achieves an equal or better visual effect. For a small Slovenian business, this mainly means one thing: loading speed and stability are often more important than complex animations. A customer who has to wait three seconds for an unnecessary 3D effect to load will have already opened a competitor's website by then.

This doesn't mean animations and interactive elements are bad. On the contrary, a well-thought-out animation, for example when adding a product to a cart, confirming a booking, or displaying a price, can noticeably improve the user experience and build trust in your brand. The difference lies in the approach: a deliberate, purposeful animation that you control down to the last detail is always a better choice for a small website than a heavy physics system trying to simulate reality while actually just slowing the site down.

Practical advice and what it means for your website

When you're thinking about redesigning or building a new website, keep the following in mind:

• Ask your developer why they're proposing a particular technology. "Because it's modern" isn't a good enough answer, it needs to tie back to your business goals, such as faster loading times or better conversion of visitors into customers.
• Check how the site behaves on a mobile phone with a slower connection. Most Slovenian website visitors today browse on mobile, so speed on that device is critical.
• Require that every animation or interactive element justify its own existence, meaning it should have a clear purpose rather than just being there for visual flair.
• Consider the long-term maintenance costs. More complex technologies, such as physics engines, often require more time for updates and bug fixes, which shows up on your website maintenance bill too.

At Carpolab, every project starts from the same principle the Stress Release team used: we first define what the website needs to achieve, and only then do we choose the technology. If you need a fast, stable, and visually appealing website that doesn't sacrifice speed for trendy technical solutions, you can get an estimate for your project through our calculator, where in just a few minutes you'll get a rough idea of the scope and cost of building it.

Frequently asked questions

Do animations on a website slow down loading? It depends on how they're implemented. Poorly optimized animations, especially those built on heavy physics engines or large video files, can noticeably slow down a site. Lightweight, purposeful animations, like the Lottie example described above, can have minimal impact on speed when a developer implements them correctly.

Does my business even need animations on its website? Not every business needs complex animations. For many small businesses, a clear structure, fast loading, and an easy path to a contact form or phone number matter far more. Animations make sense when they concretely support a business goal, such as highlighting a sale price or making a service easier to understand.

How do I know if my current website is slow because of unnecessary technical choices? The easiest way to check is to open the site on a mobile phone with a weaker connection and see how long it takes to load. If you have doubts or want an expert opinion on what could be improved, you can reach out to us through contact, where we'll review your current website together and discuss options for improvement.