Optimizing wp-includes directory in subdirectories

Hi there,

I am in the process of trying to optimize load times on a multisite / subdirectory install. I notice that all of the calls in the <head> section use site-specific directories. For example, on the root site, the head loads a script like:

http://domain.com/wp-includes/js/jquery/jquery.js?ver=1.11.1

but on a subsite, it loads:

http://domain.com/sitename/wp-includes/js/jquery/jquery.js?ver=1.11.1

A user going through the main site to several subsites will end up loading this (and several other files) several times, defeating browser caching and slowing down page load. Is there a way to tell WP to pull all of these global includes from the main root site?

Thanks!

Joe