How are you satisfied with Grav? I tried it several times, but never got enough performance boost over WP and few templates I tried did not output a cleaner front-end code compared to WP themes.
I have several simple websites and Grav is powerful enough to handle them, but somehow I still did not find enough advantages against WP + static cache plugin.
BTW. I can admit, that use Discourse is a joy and compared to other forum solutions it’s superb (at least from my front-end user experience).