Time.frameCount

Description

The total number of frames that have passed (Read Only).

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    private static int lastRecalculation = -1;
    static void RecalculateValue() {
        if (lastRecalculation == Time.frameCount)
            return;
        
    }
}

Note: frameCount starts once all Awake functions have finished. The frameCount value will be undefined during Awake functions.