LAB.js (Loading And Blocking JavaScript) allows you load in parallel your js scripts , speeding up the process ( sometimes a lot). But also it can force that scripts are loaded in a certain order, so this way no dependencies are broken.

The developer declares a 2x speed improvement on his site.

On an ondevelopment project , with 9 js scripts and 282k without labjs the page loaded in 8 seconds and with labjs in 2.5. So we have a >3x improvement.