Как оптимизировать расчеты nativeJS на мобильных устройствах?

var objects = document.getElementsByClassName('draggable');
var target = document.getElementById('target');
var startPos;
var dragObj;
var objectSelectedCount = 0;
var widthObj,
    heightObj;
var targetOffsetWidth = target.offsetWidth,
    targetOffsetHeight = target.offsetHeight,
    targetOffsetLeft = target.offsetLeft,
    targetOffsetTop = target.offsetTop;

function inArray(arr, elem) {
    for (var i = 0; i < arr.length; i++) {
        if (arr[i] === elem) {
            return true;
        }
    }
    return false;
}

document.addEventListener('touchstart', function(event) {
    event.preventDefault();
    event.stopPropagation();

    if(inArray(objects,event.target)){
        dragObj = event.target;
        widthObj = parseInt(getComputedStyle(dragObj).width)/2;
        heightObj = parseInt(getComputedStyle(dragObj).height)/2;
        startPos = dragObj.style.WebkitTransform;
    }else{
        dragObj = null;
    }

}, false);

document.addEventListener('touchmove', function(event) {
    // event.preventDefault();
    // event.stopPropagation();
    if(dragObj){
        var touch = event.targetTouches[0];
        var touchOffsetX = touch.pageX - widthObj;
        var touchOffsetY = touch.pageY - heightObj;

        dragObj.style.WebkitTransform="translate("+touchOffsetX+"px,"+(touchOffsetY)+"px)";

        if(
            (event.changedTouches[0].pageX > targetOffsetLeft) &&
            (event.changedTouches[0].pageX < (targetOffsetLeft + targetOffsetWidth)) &&
            (event.changedTouches[0].pageY > targetOffsetTop) &&
            (event.changedTouches[0].pageY < (targetOffsetTop + targetOffsetHeight))
        ){
            var color = getComputedStyle(dragObj);
            target.style.boxShadow =  color.backgroundColor + '0 0 38px 10px';
        }else{
            target.style.boxShadow =  '0 0 38px 10px rgba(255,255,255,1)';
        }
    }

}, false);

document.addEventListener('touchend', function(event) {
    // event.preventDefault();
    // event.stopPropagation();

    if(
        (event.changedTouches[0].pageX > targetOffsetLeft) &&
        (event.changedTouches[0].pageX < (targetOffsetLeft + targetOffsetWidth)) &&
        (event.changedTouches[0].pageY > targetOffsetTop) &&
        (event.changedTouches[0].pageY < (targetOffsetTop + targetOffsetHeight))
    ){
        dragObj.remove();
        objectSelectedCount = objectSelectedCount + 1;
        if(objectSelectedCount >= 3){
            window.location.replace('/site/get-product');
        }
    }else{
        dragObj.style.WebkitTransform=startPos;
    }

}, false);