Local variable problem inside event in javascript

I am shooting a page that has a large and draggable div. I have attached mousedown, mousemove and mouseup event handlers to this div.

The problem is with the mousemove event handler. I have to get the current width, height, top and left of the div. For this, I use functions to return specific values, and I have to use those values ​​in different conditions inside the main function.

If I try to assign local variables with these values ​​and use those variables in the previous code, then the script becomes slow. This means you can resize and drag.

But if I call the functions every time instead of using these variables in the condition, then there is no delay.

What will be the cause of this problem?

Sample code

// Code executes with a delay
function AdjustElement()
{
     var elemHeight = GetHeight ( elem );
     var elemWidth = GetWidth ( elem );
     var elemTop = GetTop ( elem );
     var elemLeft = GetLeft ( elem );

     if ( elemLeft >= 20 && elemRight <= 200 )
     {
        //code for moving element
     }
     if ( elemTop >= 20 && elemTop <= 200 )
     {
       // code for moving element
     }
     if ( elemHeight >= 60 && elemHeight <= 300 )
     {
       // code for resizing element
     }
     if ( elemWidth >= 60 && elemWidth <= 300 )
     {
       // code for resizing element
     } 
}

// Code executes without delay
function AdjustElement()
{
     if ( GetLeft(elem) >= 20 && GetRight(elem) <= 200 )
     {
        //code for moving element
     }
     if ( GetTop(elem) >= 20 && GetTop(elem) <= 200 )
     {
       // code for moving element
     }
     if ( GetHeight(elem) >= 60 && GetHeight(elem) <= 300 )
     {
       // code for resizing element
     }
     if ( GetWidth(elem) >= 60 && GetWidth(elem) <= 300 )
     {
       // code for resizing element
     }
}


// General functions
function GetWidth(elem)
{
   return elem.offsetWidth;
}

function GetHeight(elem)
{
   return elem.offsetHeight;
}

function GetTop(elem)
{
   return elem.offsetTop;
}

function GetLeft(elem)
{
   return elem.offsetLeft;
}