What do you use to make codeigniter app's GUI more usable and faster?

[eluser]CARP[/eluser]
Hi guys
I guess the subject/question resumes all.
I'm starting development of a (let's say) big app with codeigniter, and the main request for it is to be:

1- fast. Not only fast loading but to have less requests and reduce page reloads
2- usable
3- responsive

I solved some items by going with a simple lightweight twitter bootstrap, but would like to learn which other tools do you use to make these things possible and to accelerate development of these

For example: a jQuery plugin for MDI windows, and such

Thanks!

[eluser]CroNiX[/eluser]
For number 1, I'd enable CI page caching. If the cached page exists, most of CI doesn't even have to load like the controllers, models, custom libraries, etc. It just sends the existing cached page. If it doesn't exist, it executes the rest of CI and generates the page for the next time a user accesses it. Then if anything gets updated in the backend (content changes), delete the cached entry for that page/pages and it will regenerate them when a user visits the page next.