The JavaScript is enqueued with the footer flag set to true, so in properly coded themes, it will render in the footer, not blocking DOM loading. It only potentially blocks other external scripts, which is generally considered standard practice for scripts that have dependencies such as jQuery. This is because load order must be preserved. Async loading that preserves execution order is not well supported (in fact, IE is the only supporting browser), and is certainly not supported by WordPress’s best practices.
If you are attempting to shorten load times, this mark from Google is likely a red herring, and not the underlying cause of any perceived slowness. I would suggest looking at server response times, resource sizes, and number of includes as much more important factors than a couple of kilobytes of JavaScript.
In terms of minifying and combining your css and JS, there are plenty of plugins such as T3, Autoptimize, and Better WordPress Minify that you could look at to combine all your external resources into single files. However, none of these work well without significant manual tweaking.