To increase the loading speed of an Ecwid store, you can start loading Ecwid resources even before a customer opens the store page by the means of so-called prefetching (prerendering) browser feature. Not all browsers support this at this moment though.
DNS Prefetching of Ecwid's resources
<link rel="dns-prefetch" href="//images-cdn.ecwid.com/">
<link rel="dns-prefetch" href="//images.ecwid.com/">
<link rel="dns-prefetch" href="//app.ecwid.com/">
Prefetching and prerendering of storefront page
<link rel="prefetch" href="http://www.example.com/store/"/>
<link rel="prerender" href="http://www.example.com/store/"/>
You can also add your storefront page to preload and prerender in the background for further increase in loading speed for browsers that have this feature.
Feel free to learn more about these techniques in https://css-tricks.com/prefetching-preloading-prebrowsing/