list_renderer.js

function renderList(list) {
    var $list = $(list);
    var $container = $list.parent();
    var $items = $list.find('.list-item');

    var count = $container.height() / 68;
    var offset = $container.scrollTop() / 68;

    $items.each(function(idx, el){
        if (el.style.webkitTransform) {
            var idx = parseInt(el.style.webkitTransform.match(/translateY\((\d+)px\)/)[1]) / 68;

            if (idx >= (offset-1) && idx <= (count+offset+1)) {
                el.style.display = 'block';
            } else {
                el.style.display = 'none';
            }
        }
    })
}

var _renderList = _.throttle(renderList, 200);

$('.instance-list').each(function(idx, el){
    _renderList(el);

    var renderInterval;
    var repaintNeeded = true;

    $(el).parent().off('scroll');
    $(el).parent().on('scroll', function(evt){
        if (repaintNeeded) {
            
            $(evt.target.children[0]).find('.list-item').each(function(idx,el){
                el.style.display = 'block';
            })

            repaintNeeded = false;
        }

        clearInterval(renderInterval);
        renderInterval = setInterval(function(){
            _renderList(evt.target.children[0]);
            repaintNeeded = true;
        }, 500)
    })
});