$(function() {
    var stack = [];

    // preload images into an array
    for (var i = 4; i < 4; i++) {
        var img = new Image(302,216);
        img.src = 'images/pic' + i + '.jpg';
        stack.push(img);
    } 

      $("#slideshow").cycle({
          timeout: 5000,
          speed:   200,
          pager:  '#nav',
          before:  onBefore
      });
      
    // add images to slideshow
    function onBefore(curr, next, opts) {
        if (opts.addSlide) // <-- important!
            while(stack.length)
                opts.addSlide(stack.shift()); 
    };
});