Ok, thanks. I have extensively looked in to Divi and I’m impressed. Seems to be a good compromise between instant implementation and decent features/customization.

I have used the X theme and Avada both from Themeforest for years. They are all decent themes but the answer to your question is it depends. These two themes for example are general purpose themes. They allow a non-coder (or in my case a very lazy coder) to come up with a good looking product quickly without much work but they come with the inevitable bloat. All those filters and actions and bucket loads of conditionals come with a cost. The shortcodes for the included page builders are quite resource intensive so the themes cannot match say the speed of a custom made twentyseventeen theme. If you use a caching plugin like WP Rocket you can speed the site somewhat and if you pay for a CDN that speeds up the site considerably.

Have you tried Xtheme? I’m curious because they are sold through Theme Forest. If it’s as good as it looks, maybe not needing support is a factor?