Michael, Below are some WP theme speed-related benchmarks I personally completed a while back - You can view my methodology here
(skip to the theme section towards the bottom). I'm sure you can find more scientific benchmarks out there as well on a theme-by-theme basis (anyone else know of some good benchmarks for WP themes?). You mentioned Genesis, and that performed near the top of my results, so if you like what you see there, I'd say go for it! The biggest surprise for me was that Beaver Builder performed near the top and better
than many non-builder themes (I've been on the Beaver Builder bandwagon since - I'll eat crow and humbly throw Divi into the dumpster fire, Nick!). I didn't test Elementor (Sorry, Matt!), but maybe I'll add that in the future when GEEKWAP sponsors my next tests.