Performance

    React is built for performance; React is used to build massively complex interfaces with thousands of elements, each one potentially responding to user interaction.

    Because performance is so fundamental to React, it can be helpful to understand the performance model of various operations at a high level.

    Performance model

    Operation
    Cost
    Description
    Native UI manipulationSlowReact attempts to modify the native UI as little as possible.
    Component renderFastIt's common for component functions to be called many times as the props of a component change. We often call this rendering. Components can re-render very frequently without a noticeable performance impact.
    Comparing propsVery fastIn cases where a component is rendering too frequently and causing performance issues, we can limit the amount of re-renders by only re-rendering when props actually change. We'll cover this in more detail in the next section.

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