In jQuery UI we can exclude the effect which we don't need and can make the lightweight library for project. see here http://jqueryui.com/download
in Mobile cache is not much like desktop browsers
By default jquery mobile add
jQuery core, 31KB as we've seen
jQuery Mobile specific code, 20KB
CSS rules, 7KB
I also want to remove unneeded things from CSS too because by default jQuery has 5 different themes.