scribu

This plugin improves the gallery template by making the following tweaks:
<ol>
<li>Puts all the gallery css in a separte file, for easy customisation and faster page load.</li>
<li>Adds an id attribute to the code, so that two or more galleries can have a different number of columns and still display correctly on the same page.</li>
</ol>
Links: <a href="http://scribu.net/wordpress/improved-gallery" rel="nofollow ugc">Plugin News</a> | <a href="http://scribu.net" rel="nofollow ugc">Author’s Site</a>

Improved Gallery

Improves the built-in gallery in WordPress 2.5 and newer.

noughtdigital

Jake Henshall

Remove /xmlrpc.php from code if XML-RPC is disabled 
Remove WordPress API from code if WP-JSON is disabled 
Disable Google Maps 
Disable WooCommerce scripts and CSS on non-WooCommerce pages 
Disable WooCommerce Reviews 
Defer WooCommerce Cart Fragments 
Remove WordPress API from header 
Disable self-pingbacks 
Disable emojis 
Disable embeds 
Remove query strings 
Disable XML-RPC 
Remove jQuery migrate 
Remove WordPress version number 
Remove wlwmanifest link 
Remove RSD link 
Remove shortlink 
Disable RSS feeds 
Remove RSS feed links 
Disable WordPress heartbeat API 
Disable and Limit Post Revisions 
Change Heartbeat API frequency 
Change autosave interval 
Add Locally hosted Google Analytics Script 
CSS and JS Script Manager 
Import and Export feature
<h3>From within WordPress</h3>
<ol>
<li>Visit ‘Plugins > Add New’</li>
<li>Search for ‘Whippet’</li>
<li>Activate Whippet from your Plugins page.</li>
</ol>
<h3>Manually</h3>
<ol>
<li>Upload the <code>whippet</code> folder to the <code>/wp-content/plugins/</code> directory</li>
<li>Activate the Whippet plugin through the ‘Plugins’ menu in WordPress</li>
</ol>

Whippet

Improve your WordPress Speed: Easily remove unnecessary features from WordPress to help speed up your site.

Improved Gallery vs Whippet