Fastest Woocommerce ThemeQuickest Woocommerce Topic
EXCLUSION OF LIABILITY: This answer concentrates more on the WooCommerce/Wordpress page performance issues than WooCommerce kid issues for obvious reason that will help you further on. I tried many, but at the end I developed my own Venedor children's theme. One pretty big dilemma at the moment is that 3. 1 WooCommerce releases have not been well co-ordinated with the developer base, and this goes for topics and children's topics along with all the other very useful WooCommerce plugins and enhancements.
The Venedor customized theme had to be fixed because it did not work with the 3.1 WooCommerce release and had the same problems with many plug-ins. Altogether, I am now satisfied with my Venedor customized kid theme, but I always try to use a default kid theme whenever possible.
Simply make sure before installation that it is compliant with the WooCommerce release you are using. In terms of performance, the topic cannot be quicker than Wordpress/WooCommerce itself, and from my point of views this is not a very quick loader. You can use a caching/CDN to accelerate your whole website, such as WP Fastest Cache, WP Super Cache or WP Rocket.
They are not all suitable for every single WooCommerce page or Wordpress as well. In fact, I use all three, according to how well they are playing with my Wordpress template and/or WooCommerce. They all have plug-ins that you may or may not need based on your power.
They all contain CDN (Content Distributions Network), where you can really see the increase in performance. In order to test your page loading performance, I suggest PageSpeed Insightsby Google. The WP Super Cache is the simplest. The WP Fastest Cache has more config settings, and the WP Rocket has the most config settings of all.
Apart from that, I'd choose a WooCommerce theme that comes close to the UI/UX expertise you're looking for, but again, make sure it's compliant before you do. Just set it up to your heart's desire and don't care too much about the pace until you get the look you want.
Begin with the WP Super Cache. Then if you don't get two blank flashes in Page Insights, go to the WP Fastest Cache and try again, sometimes several of the same steps. If everything else goes wrong, go to WP Rocket and take full advantage of the many top-of-the-line choices they have, but do this one by one and always test the effectiveness of the function with Page Insights.
Remember that the more you use plug-ins, especially those based heavily on Java Script, the more slowly your website may be loaded, so as an extra precaution you can disable all the plug-ins you have tried, but no longer use, to keep your resource to a bare minimum. What's more, you can also disable all the plug-ins you've tried.