Is the Universal Selector a Performance Killer?

The Universal Selector: Friend or Foe of Performance?

In a quest to optimize page performance, the question of the universal selector (*) arises. Concern swirls about its potential impact on speed, prompting an investigation into its true performance characteristics.

The Universal Selector's Effect

In essence, the universal selector applies a CSS rule to every element in a document. This means that the following CSS:

<code class="css">* {
  margin: 0;
  padding: 0;
}</code>

is equivalent to:

<code class="css">body, h1, p {
  margin: 0;
  padding: 0;
}</code>

Performance Implications

In modern browsers, the performance impact of the universal selector is negligible. This holds true even for cases where it is applied to a considerable number of elements. However, it is crucial to note that this is only the case when it is used for "fast" effects like margin and padding. Applying slower effects, such as box-shadow and z-axis rotation, to every element can lead to a performance hit.

The Universal Selector and Slow Rendering

The misconception that the universal selector is inherently slow stems from its history. In the past, browsers often had difficulty parsing large CSS selectors, resulting in slow rendering. However, advancements in browser technology have addressed this issue, making the universal selector perform comparably to other selector types.

Conclusion

Based on current evidence, the universal selector, when used judiciously for fast effects, has negligible performance impact. While it may have earned a bad reputation due to past experience, it is no longer a performance hindrance. Therefore, it is perfectly acceptable to use the universal selector as intended to apply a rule to all elements in a document, especially if brevity is desired.

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