jQuery or CSS3 transitions? Speed comparison + brief empirical explanation. 15 years ago
Sure, native tweening is fast and great, but don't show it by performing a false comparison.
The CSS transition is performing a single tween on a CSS rule; the div tags just inherit the result. The jQuery test is performing inline style tweens ... on every div! First of all you're performing redundant/duplicate calculations. Second of all, you're throwing away all performance gains you had by having shared css render style objects.
A better test would of been to update the style sheet via JS.