Function leptos_reactive::create_render_effect

pub fn create_render_effect<T>(
    f: impl Fn(Option<T>) -> T + 'static
) -> Effect<T>
where
    T: 'static,

Creates an effect exactly like create_effect, but runs immediately rather than being queued until the end of the current microtask. This is mostly used inside the renderer but is available for use cases in which scheduling the effect for the next tick is not optimal.