What is the benefit from using jquery mobile plugin?

1- Themes - You can easily theme your application with jQuery Mobile ThemeRoller 2- Plugins - There are probably hundreds of jQuery Mobile plugins available. 3- Fast prototyping 4- Large community

you mean for easy and fast solution to build mobile site, but about the performance it's not help me, because it's need the Jquery core and sometimes Jquery UI, i think we can built our theme or another plugin with high performance, i know this will take extra time but we care of performance, but i think the most important benefit is because it's employs the capabilities of jQuery core, HTML5 and CSS engaging touch-screen UI.

Easy and fast solution to build mobile site, he is the best way to use OnePage ( Full + Slider ) but when we talk about performance he is not the best solution. 

The most benefit of using jQuery mobile is to create a single page application !

I think using Responsive Design ( RWD ) strategy will solve the major issue using Jquery Mobile Plugin, check this link: http://www.islamzatary.com/responsive-web-design-rwd-approach/