Dana Ross

HTTP/2 is the new generation of the venerable HTTP protocol that powers the web. Among its most powerful features is server push, a way for web servers to send resources to the browser before it even realizes it needs them. This avoids the usual HTTP request/response cycle which happened for every script or stylesheet on a page.
This plugin enables WordPress to send a <code>Link:<...> rel="prefetch"</code> header for every enqueued script and style as WordPress outputs them into the page source. Unfortunately, it can’t help plugins and themes that output their scripts directly into the page itself, but these will continue to work as they always have.
Requires a web server that supports HTTP/2.
<h3>WordPress 4.6 and above</h3>
WordPress 4.6 introduced <a href="https://make.wordpress.org/core/2016/07/06/resource-hints-in-4-6/" rel="nofollow ugc">native support for resource hints</a>. 
By default, this plugin defers to WordPress 4.6 and theme/plugin developers to responsibly prefetch the right assets. Sites running 
on older versions of WordPress will continue to get the previous behavior where all JavaScript and stylesheets had resource hints 
printed for them.
I’ve added a filter To restore the old behavior (hint everything) on WordPress 4.6 and above. To use it, add this line to 
your theme’s functions.php file or a custom plugin:
<pre><code>`add_filter('http2_render_resource_hints', '__return_true');```
</code></pre>

HTTP/2 Server Push

This plugin helped speed up my website by 33%!

Works as advertised

This plugin does just what it says it'll do, HTTP/2 pushes everything!  

That generally will speed things up unless you have a ridiculous number of assets.  

While it now respects resource hinting for themes and plugins that provide that info, I do wish it had a UI for older themes/plugins to control what assets were going to be pushed instead of pushing them all. This plugin is so great without that though it still gets 5 stars

Speeds things up

Works perfectly in conjunction with Cloudflare to deliver excellent performance

Works perfectly

Enables HTTP/2 server push for local JavaScript and CSS resources.

PI Web Solution

<ul>
<li>
Push / Pre-load all JS files in site with one simple option
</li>
<li>
Push / Pre-load all the CSS files in your website
</li>
<li>
Push / Pre-load other resources throughout the site or based on the page types
</li>
<li>
Load CSS Asynchronous or Remove any CSS file throughout the site, or there is a conditional selector that you can apply
</li>
<li>
Async / Defer / Remove any JS file throughout the site or based on the WordPress page type
</li>
<li>
You can create mobile device specific rule to push, pre-load, remove, async js or css, this works based on the device user agent detection
</li>
<li>
You can create desktop device specific rule to push, pre-load, remove, async js or css, this works based on the device user agent detection
</li>
<li>
Conditionally remove JS and CSS from various WooCommerce pages like checkout page, cart page, product page, product category page
</li>
<li>
You can push pre-load resource specific on some pages by their ID
</li>
<li>
Remove CSS, JS specific to page or post by their ID
</li>
<li>
Organize rules in group for easy management of the rules
</li>
<li>
Remove CSS, JS on all pages leaving only on the page you specified
</li>
<li>
optimize WooCommerce speed
</li>
<li>
optimize WordPress website speed
</li>
</ul>
<iframe loading="lazy" class="youtube-player" width="750" height="422" src="https://www.youtube.com/embed/GHGclxgbSqI?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe>
<blockquote>
Mobile and Desktop detection works based on the wp_is_mobile() function of the WordPress that detect device based on the user agent data send in the request
</blockquote>
Apart from this it also offer ability to remove Css and JS file from specific pages based in the selected page tag conditions
Eg: if css path is https://s.w.org/style/wp4.css
then you can match it with wp4.css or style/wp4.css or s.w.org/style/wp4.css
you use 2nd method (style/wp4.css) for more precise selection (this avoid error when there are 2 style with same file name)

Page Speed Optimizer: HTTP/2 Push, Async JavaScript, and Defer CSS

My websites are entirely in AMP, but this plugin injects non-AMP scripts on evey page. It doesn't even try to inject scripts only in non-AMP. So, kinda useless for me. I hope to give it another try in the future.

Not compatible with AMP

It is one of my mandatory plugins, I always use it. :)

Simple, handy and must-have :)

HTTP2 Server push, Async JavaScript, Defer Render Blocking CSS, with fine rule set to control js and css on different page types,

HTTP/2 Server Push vs Page Speed Optimizer: HTTP/2 Push, Async JavaScript, and Defer CSS