Pagespeed Insights provides scores for both mobile and desktop page loading. Bearing in mind there are around 50% of your users who are visiting your website using their mobile phones, so faster page load is important. Any slower they'll go off somewhere else.
WIX and Squarespace
How do we achieve these scores for a CMS? First of all we use Joomla, our choice for CMS. Then we sprinkle a bit of magic. Seriously, we optimise and optimise. All websites develop by us and under our hosting will undergo this optimisation.