How v-once and v-memo Optimize the Vue Render?

v-once and v-memo are directives used for optimizing components with reactive data that:

• Never changes/Doesn’t impact UI: If the data is declared reactive but never intended to update or not needed to be reflected visually. v-once directive is used to render elements just once, avoiding further updates.
• Update depends on specific data change: For more granular control we use v-memo. This directive allows to define an array of dependencies. The element wrapped with v-memo will only re-render if one of the values in the dependency array changes. This is ideal for components with large amounts of data where only specific changes require an update to UI.

A v-memo with no dependencies works like v-once, meaning it only renders the element or component once.

Rendering speed is crucial for a good user experience in modern apps. Out of all ways, one extremely easy way to optimize rendering is by only re-rendering what needs to be. While Vue re-renders components when their data changes this can lead to inefficiencies. v-once and v-memo directives offer a solution by allowing control over re-rendering, improving performance.