Best Speed Wordpress Theme

Schema in opinion best theme for SEO purposes and very optimized for speed. You can use it with simple page builder, such as Elementor and it will be just fine.
But you will need to design your site with this theme. If you don't have design skills just go for WP Astra / GeneratePress.

You can test out different theme demos before even installing them, and you will be shocked that even their demos have low speed rating, with/without cache plugin.

So you should do your tests, and you will understand which is best for you. Just get a theme that uses the least plugins as possible. The less plugins = the better. Because as soon as your database start to grow, these plugins going to hold your website back, and slow your site, which will require you to buy better and faster hosting.

Generatepress is much better than others.

There is fastest seo WordPress theme by Mythemeshop

I suggest mythemeshop

GeneratePress

I made one by myself, i remevoed every piece of javascript and left only php/html and css!