Chris J. Zähller

In its default settings, Contact Form 7 loads its JavaScript and CSS stylesheet on every page. This slows page loading and taxes server and client resources. Use this plugin to control which pages the scripts load on.
NEW in v1.0.15: The plugin also prevents scripts and styles from the following plugins from loading. If you are using any other plugin that extends Contact Form 7 and loads its scripts on all pages, please open a support ticket and we will look into adding it.
<ul>
<li>Contact Form 7 Conditional Fields</li>
<li>Contact Form 7 Multi-Step Forms</li>
<li>Contact Form CFDB7</li>
<li>Drag and Drop Multiple File Upload — Contact Form 7</li>
</ul>
<h3>Translations</h3>
<ul>
<li>English: Default language, always included</li>
</ul>
Would you like to help translate Conditionally Load CF7 into your own language? <a href="https://translate.wordpress.org/projects/wp-plugins/cf7-conditional-load" rel="nofollow ugc">You can do that here!</a>

Conditionally Load CF7

Load Contact Form 7 & select CF7-related plugin scripts & styles only where needed.

jimbo2150

This plugin extends the WP_Scripts class, adding some additional methods and filters that overload the existing script output to add Require.js syntax. It loads scripts via Require.js and by default defers until the DOMContentLoaded event fires (unless a manually added require() is called within the head/body and does not wait for the DOM to be loaded. 
It is designed to work in conjunction with HTTP/2 but will function fine without it (though you may see slower load times).
This plugin is design to assist developers in updating and creating JavaScript that is asynchronous – that is, scripts that can load in a different order and do not assume that their dependencies are available immediately. Use of the Asynchronous Module Definition (AMD) allows a script to define it’s dependencies and have them loaded asynchronously prior to the entire script or the initialization portion executes.
It is common for larger projects to concatenate together scripts however, they can end up a jumbled mess and smaller required functions are often duplicated (and redundant) across multiple scripts. HTTP/2 corrects this by allowing multiple resource files to be requested and downloaded within a single TCP window. As projects get larger and more diverse it is becoming more economical to load the individual components (modules) that are needed rather than download and execute one massive concatenated script file (which can also cause the browser to freeze up).
NOTE: This plugin currently only replaces non-administrative (front-end) scripts with Require.js syntax.
Plugin website: https://techie-jim.net/wordpress-plugins/requirewp/

RequireWP

Uses Require.js to load scripts faster and speed up WordPress / increase site load speed & performance. Designed to work with HTTP/2.

Conditionally Load CF7 vs RequireWP