Camera Smoothness issue.. Please help..

Hi Guys, I have GUI.Repeat Button to control my camera in OnGUI() in GUIHandler.cs In CameraHandler.cs, i have an update loop, which is processing the deltaX & deltaY sent by GUIHandler.

Problem with below code is i m not getting a smoothness while rotating camera. its lagging. Please tell me whats wrong with this code?

GUIHandler.cs

 if (GUI.RepeatButton(cameraHandlerBounds, textureCamera, GUIStyle.none))    
         {    
             Vector3 mousePosition = Input.mousePosition;    
             mousePosition.y = Screen.height - mousePosition.y;    
             //Debug.Log("Clicked the button with an image: " + mousePosition + "  center: " + cameraHandlerBoundsCenter + "  MaxDist: " + maxDistance);    
             distanceCovered = Vector3.Distance(mousePosition, cameraHandlerBoundsCenter);
 
             if (distanceCovered > maxDistance.x)    
             {    
                 Debug.Log("Out of Bound");    
                 if (isControlInbound)    
                     isControlInbound = false;    
             }    
             else    
             {                    
                 deltaX = mousePosition.x - cameraHandlerBoundsCenter.x ;    
                 deltaY = cameraHandlerBoundsCenter.y - mousePosition.y;    
                 deltaX = Mathf.Clamp(deltaX, deltaXPre - 0.15f, deltaXPre + 0.15f);    
                 deltaY = Mathf.Clamp(deltaY, deltaYPre - 0.15f, deltaYPre + 0.15f);    
                 deltaXStore = deltaX;    
                 deltaYStore = deltaY;                   
 
                 if (!isControlInbound)    
                     isControlInbound = true;                                 
 
                 deltaXPre = deltaXStore;    
                 deltaYPre = deltaYStore;     
 
                 cameraHandlerRef.deltaX = deltaX;    
                 cameraHandlerRef.deltaY = deltaY;    
             }    
         }

CameraHandler.cs

             float rotationX = transform.localEulerAngles.y + (deltaX * Time.deltaTime); //Input.GetAxis("Mouse X") * sensitivityX;                

             rotationY += (deltaY * Time.deltaTime );

             rotationY = Mathf.Clamp(rotationY, minimumY, maximumY);

             transform.localEulerAngles = new Vector3(-rotationY, rotationX, 0);