gazchap

By default, WooCommerce will only show thumbnails for categories if the category has a thumbnail set.
This plugin changes this behaviour so that WooCommerce will hunt for a product thumbnail in the category being displayed, and use that instead.
Upon activation, the plugin will configure itself with the basic settings. Any categories that you have on your WooCommerce store that do not have a thumbnail set will then start displaying any available product thumbnails inside the category.
There are a number of options, these can be found in WooCommerce -> Settings -> Products -> Auto Category Thumbnails.
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Thumbnail Size sets the image size that the plugin should use when displaying the thumbnails. Defaults to shop_thumbail, but shop_catalog may be a better option for some themes.
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Go into Child Categories makes the plugin look in child categories too, useful if you have products buried in quite a deep category structure.
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Random Thumbnail tells the plugin to pick a random product thumbnail from those it finds every time the page loads – otherwise it always uses the first one it finds.
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Use Transients tells the plugin to save the thumbnail it picks for a category as a transient in WordPress, so that it won’t have to do it again while the transient is still active. This can hugely increase performance on sites with many categories, so is enabled by default.
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Transient Expiry is the length of time each transient is active for before the site picks another thumbnail for the category. By default it is set to 1 day.
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Custom Transient Expiry can be used to define your own transient expiry period (in seconds) if none of the pre-defined options are suitable.
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Exclude Thumbnail IDs accepts a comma-separated list of attachment IDs from the WordPress Media Library. The plugin will never use any thumbnail with one of these IDs for a category.
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<h3>License</h3>
Licensed under the <a href="http://www.gnu.org/licenses/gpl-2.0.html" rel="nofollow ugc">GNU General Public License v2.0</a>

GazChap's WooCommerce Auto Category Product Thumbnails

Pick WooCommerce category thumbnails automatically from products contained within those categories.

Jumedeen khan

Mozedia

Lazy Load for Images plugin make lazy load WordPress Images with less then 2kb small pure javascript code, no need jQuerry.
It’s help to increase performance of your website and make it fast loading and improve your website SEO rankins.
This plugin make lazy load of all type images like thumbnail, post content images, avatars, gravatars, widget images .etc.
All images load only when users scroll down and they are on viewport. It’s SEO and user friendly, working well with all browsers.
This plugin is structured very simple and does not need any settings. Activate it, Done!
<blockquote>
<h4>Lazy Load for Images – Features & Advantages</h4>
<ul>
<li>Load images only when required.</li>
<li>Improve page loading speed.</li>
<li>Reduce no. of HTTP requests.</li>
<li>Lazy load also working on mobiles.</li>
<li>Plugin used pure JS, no need of jQuery.</li>
<li>Plugin used less than 2kb Javascript.</li>
<li>Also support Gravatar.</li>
<li>Also support Genesis Framework.</li>
<li>SEO friendly (search engine optimized).</li>
<li>Worked great with genesis framework.</li>
<li>No need configurations (Just activate it, It’s Done!)</li>
<li>Of course, available on <a href="https://github.com/jumedeenkhan/lazy-load-for-images" rel="nofollow ugc">GitHub</a></li>
</ul>
</blockquote>
Simply install the plugin to enjoy a faster website. No options are available : you install it and the plugin takes care of everything.

Lazy Load for Images

A must-have for the fastest page load time, save bandwidth cost. Just install and activate and your site is ready to load with Rocket speed. Awesome work, Highly recommended! 

💯 Excellent plugin, Improves Page Load time Instantly ⚡

Lazy Load WordPress images with a small javascript. Load images only after scrolling down and when viewport and improve page speed and SEO rankings.

GazChap's WooCommerce Auto Category Product Thumbnails vs Lazy Load for Images