First of all, I want to say that Basel is an amazing theme. Great job.
I am testing my website with gtmetrix and I found out that I have issues with the parsing of javascript files during the initial load, causing a slow page load. Also the file /wp-content/themes/basel/js/theme.min.js?ver=4.6 is the heaviest of all with almost 300kb. Can we find a workaround to fix this?
If you will take a look at all JS files that you have on your web-site you will see that our theme includes only one JS file and it doesn’t load at the initial loading and doesn’t cause any performance issues. And 300kb it is not too much taking into account that this file contains all libraries and custom scripts needed for our theme work.
Almost all plugins and WordPress itself add additional JS and CSS files to your page. We suggest you to use some plugin for optimizing and combining them all into one JS and one CSS files to improve your site’s performance. As an example we suggest you to try W3 Total Cache plugin.