How can I update a old theme, for better look and speed similar to bootstrap ?

[2013]

How can I upgrade a old wordpress theme, improve look and speed ?

The theme I'm using has a feature rich backend, but the front end is not as fast as it could be and looks is a bit dated now.


I thought, maybe upgrading the framework (bootstrap or purecss) in a child theme and not the main theme, would this be possible and would it work.

 

[2013]

I'n basic yes, I wanted to improve it, in both the look and speed, similar to the modern bootstrap themes.give it some modern effects and features.