Time.frameCount

Description

The total number of frames since the start of the game (Read Only).

This value starts at 0 and increases by 1 on each Update phase.

Internally, Unity uses a 64 bit integer which it downcasts to 32 bits when this is called, and discards the most significant (i.e. top) 32 bits.

using UnityEngine;

public class Example : MonoBehaviour
{
    // Makes sure that RecalculateValue only performs
    // some operations once per frame and no more.
    static private int lastRecalculation = -1;

    static void RecalculateValue()
    {
        if (lastRecalculation == Time.frameCount)
            return;
        //  ProcessData.AndDoSomeCalculations();
    }
}

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