Hi,
You can try rocket loader or similar solutions, but if your scripts are loaded in the site footer already (non-blocking), then the execution time is not noticable to users whatsoever – regardless of the measured time. Even using rocket loader the scripts are still executed, but may not show up on the measurement tool – but that does not mean it is better whatsoever, as they still need to be executed.
Personally, I would not bother with external script loaders, as WordPress has a preferred order of loading jQuery and other prerequesites, some may also have event handlers on the page load event etc.. If your page loads up nicely, is properly cached, then by the time the user starts scrolling the scripts are already executed.