Poor performance in mobile

[hendrasan]

I just test this plugin in iPad (and this applies in mobile overall I guess), and it is quite poor performance-wise.

As I need quick fix for my project, I modified your plugin a bit. The main culprit is the jQuery animate call which has horrible performance in mobile, so I change that to CSS3 animation and it's much better. However, as it's quick fix and probably has lots of issues, I can't open a pull request.

I just thought I should let you know about this.