How to optimize this script and add items imediately without grids

How can i optimize this inventory script. And also pick up items and drop them. The items are in c#. i Tried converting this script but to no avail.

 #pragma strict
 //Private Variables
 private var InventoryOn = false;
 private var scrollBarChopGrid : Vector2 = Vector2.zero;
 private var GridValue : float = -1;
 var myskin : GUISkin;
 
 //GUI Pos/Size
 var ClosePosition : Vector2 = new Vector2(312,5);
 var CloseSize : Vector2 = new Vector2(35,35);
 var NamePosition : Vector2 = new Vector2(13,13);
 var NameSize : Vector2 = new Vector2(250,250);
 var TooltipSize : Vector2 = new Vector2(140,40);
 var GridPosition : Vector2 = new Vector2(10,2);
 var GridSize : Vector2 = new Vector2(323,410);
 var ScrollPosition : Vector2 = new Vector2(0,95);
 var ScrollSize : Vector2 = new Vector2(353,257);
 var WindowPosition : Vector2 = new Vector2(0,0);
 var WindowSize : Vector2 = new Vector2(360,360);
 var DragWindowPosition : Rect = Rect(0, 0, WindowSize.x, WindowSize.y);
 
 //Textures
 var InventoryWindow : Texture;
 var CloseIcon : Texture;
 var Grids : GUIContent[];
 
 
 function Update () {
     //On or Off
     if (Input.GetKeyUp("i"))
     {
         if (InventoryOn == false)
         {
             InventoryOn = true;
         }
         else if (InventoryOn == true)
         {
             InventoryOn = false;
             scrollBarChopGrid.y= 0;
         }
     }
     //Window Drag fix
     if (Input.GetKeyDown("left shift"))
     {
     if (Input.GetKeyDown("i"))
     {
     DragWindowPosition.x = 10;
     DragWindowPosition.y = 10;
     }
     }
     }
 function OnGUI()
 {
     GUI.skin = myskin;
     if (InventoryOn == true)
     {
         DragWindowPosition = GUI.Window(0, DragWindowPosition, DoMyWindow, "");
         
         if (GridValue != 0 && GUI.tooltip != ""){
         {
     GUI.Box(Rect (Event.current.mousePosition.x, Screen.height - Input.mousePosition.y + 15, TooltipSize.x,TooltipSize.y), Grids[GridValue].tooltip);
 }
 
         }
 
     }
 }
 
 function DoMyWindow(windowID : int){
 
          if (InventoryOn == true)
     {
         GUI.BeginGroup(new Rect(WindowPosition.x, WindowPosition.y, WindowSize.x, WindowSize.y), InventoryWindow);
            //Name
            GUI.Label (Rect (NamePosition.x, NamePosition.y,NameSize.x, NameSize.y),"Your Inventory"); 
          //Close Button
         if (GUI.Button(Rect(ClosePosition.x, ClosePosition.y, CloseSize.x, CloseSize.y), CloseIcon))
         {
             InventoryOn = false;
         }
         //Scroll Bar
         scrollBarChopGrid = GUI.BeginScrollView(Rect (ScrollPosition.x, ScrollPosition.y, ScrollSize.x, ScrollSize.y), scrollBarChopGrid, Rect(0,0,0,420));
             // Grid
             GridValue = GUI.SelectionGrid(Rect(GridPosition.x, GridPosition.y, GridSize.x, GridSize.y), GridValue, Grids, 5);
         GUI.EndScrollView();
     //Dragable Window
     GUI.DragWindow (Rect (WindowPosition.x, WindowPosition.y, 10000, 40));
         GUI.EndGroup();
     }
 }