The delay is caused by the way Shopify loads websites. To achieve the best user experience, Shopify will always load your website first, and then the apps, hence the delay. When it loads the apps, it will load them one by one based on their installation order. For example, if an app is the last one installed in your store, it will be the last one to load into the storefront.
We have, however, developed a solution for this. Since the fix requires editing your theme's code slightly, we definitely recommend duplicating your theme first. This will create a clean version to revert back to if needed for any reason.
Please copy and paste the line of HTML code below in the theme.liquid file right above </body>, and then replace XXXXXXXXX to match the address of your Shopify store. For example: If your address is footballstore.myshopify.com, you would put footballstore.
It won’t completely eliminate the delay, but it should substantially reduce it. If you run into any trouble or would like us to install the fix for you, please contact us directly.