How to solve while loop lags

Hello everybody I use while loop in 2 Coroutines. 1 coroutine increase number during time and second move 2 texts during same time. I call this 2 coroutines in same function. Sometimes my android game freezes for second. Do you have any ideas how to solve this problem? Here is my code:

 IEnumerator IncreaseNumber()
     {
         float duration = 0.5f;
         float elapsed = 0;
             while (elapsed<duration)
             {
                 elapsed += Time.deltaTime;
                 graduatingNumber2 = Mathf.Lerp(0, randomValueSpeed2, elapsed / duration);
                yield return null;
            }
 }

 IEnumerator MoveSpeedTextHasTextSmoothly()
     {
         float currentTime = 0;
         float timeOfTravel = 0.5f;
 while (currentTime <= timeOfTravel)
             {
                 currentTime += Time.deltaTime;
                 secondSpeedText.rectTransform.anchoredPosition = Vector2.Lerp(startPositionSpeedTextVector2, endPositionSpeedTextVector2, currentTime/timeOfTravel);
                 secondHasText.rectTransform.anchoredPosition = Vector2.Lerp(startPositionHasTextVector2, endPositionHasTextVector2, currentTime / timeOfTravel);
                 yield return null;
             }
 }