It would be no more memory intensive than displaying them in the UI. Behind the scenes, React stores the components as objects, so there is no performance cost.

The code <Component /> transpiles to React.createElement(Component, null);, which will return an object that looks roughly like this (dev builds may include extra properties to help with debugging):

{
  $$typeof: Symbol(react.element)
  key: null,
  props: {}
  ref: null,
  type: Component,
  _owner: null,
}

Of those, the props and the type are the only things that could conceivably have a significant memory footprint. But Component is very likely referenced somewhere else anyway, so i doubt it can be garbage collected whether you create this element or not.

In short, i'd say the memory is only a problem if both of the following are true: 1) the props are very large, and 2) the props would be garbage collected if not for this element.