After working on this a week for a few weeks, I published a new design for Joomlaseo.com yesterday. It should make the site much more interactive, with the latest blogs much clearer on the homepage and also the general design is much cleaner and less distracting.
The new site was built with the Galatea theme form Rockettheme (tip: they have a spring-sale until April 5th), which already offered much of how I wanted the new design to look. Some of the default components of the template worked out of the box, like the intro-blocks on the homepage, for which default particles were present in the template. For the rest of the blog-views I used Yootheme's Widgetkit, which is one of standard tools.
Performance: 100% on Pingdom
Also the performance of the new site is fast again. After a bit of tuning I got it to score 100% again in Pingdom Tools. As I use more images,especially on the homepage, the number of resources is just slightly higer, but the site still loads in less then a second.
Of course the site runs on Joomla 3.5 and PHP 7, while I recently also switched the site SSL with Let's Encrypt (free on both Siteground and KeyCDN), so the site is ready for the future. Or at least untill Joomla 4 is out ;)
Happy browsing, and I hope you SEO fans all like the new design!