Daniel Mahaffy

The “All-in-One Event Calendar” by Time.ly works great, but uses dynamic javascript. 
This plugin creates a static version of the javascript that can be cached by 
the browser.
I have tested this plugin with versions 2.1.9 and 2.2.0 of the event calendar plugin. 
It may work with future releases, but use it at your own risk.
This plugin only uses the static javascript on the frontend. If a user is 
logged in, the original dynamic script will be used. As far as I can tell 
caching the javascript does not interfere with the plugin’s functionality, but 
there may be features of the event calendar that do not work with this plugin.

Fix Event Calendar Caching

This plugin makes the All-in-One Event Calendar's javascript cacheable to improve page load speed.

Frank Goossens

Optimizing Matters

EricJohnsonGuru

Eliminate Render-blocking Javascript in above-the-fold content with Async Javascript.
Render-blocking Javascript prevents above-the-fold content on your page from being rendered until the javascript has finished loading. This can impact on your page speed and ultimately your ranking within search engines. It can also impact your user’s experience.
Async JavaScript gives you full control of which scripts to add an ‘async’ or ‘defer’ attribute to or to exclude to help increase the performance of your WordPress website.

Async JavaScript

Plugin works as expected, settings are nice and minimal (using core styles) and there aren't any banners, notices or other marketing bloating things up.

Works great!

Async Javascript lets you add 'async' or 'defer' attribute to scripts to exclude to help increase the performance of your WordPress website.

Fix Event Calendar Caching vs Async JavaScript