I'm not convinced that's still true. Obviously I can't see google-rankings internal stuff, but...
If I search for weather, lyrics, or other common sites, the top results are always slow, bloated, JS-filled nightmares. Yet the sites that are quick and small are never to be found.
Maybe they do and they need to weight speed higher. I don't know, but I know that I don't ever seem to get fast loading results.
This feels too much like creating a problem that you want to be able to step in and solve.