"PageSpeed Insights" is advisory in nature. Testing emulates low internet speed
Flexkit and Seotoaster are as optimized as possible.
In Flexkit files 1_activate_... change true to false for elements that are not used in the project, this will reduce the css size.
For images that are added without using widgets, you can add the loading="lazy" attribute. (<img src="image.jpg" loading="lazy" alt="..." />)