Indicate that processor-heavy JS function is running (GIF spinners don't animate)

Question

Showing then hiding animated indicator / spinner gifs are a good way to show a user that their action has worked and that something is happening while they wait for their ac

Answer 1

Modern browsers now run CSS animations independently of the UI thread if the animation is implemented using a transform, rather than by changing properties. An article on this can be found at http://www.phpied.com/css-animations-off-the-ui-thread/.

For example, some of the CSS spinners at http://projects.lukehaas.me/css-loaders/ are implemented with transforms and will not freeze when the UI thread is busy (e.g., the last spinner on that page).