Only reason Safari feels fast is that it has avoided implementing features. There's still stuff that's been present in Chrome/Firefox for 10 years, but still doesn't work in Safari.
Does Google still show the old search results page design to Safari users? It did that for a long time.
If those features slow down the web then that’s a knock on those features. Plus I’ve yet to see a single one of these supposedly “missing” features actually matter in the real world.
May I recommend Orion? It's based on Safaris engine, but imo improves massively on its ui (for example it comes with a fantastic (opt-in) tree-style tab browser).
But most importantly it supports chrome and firefox extensions. Most of them do just work out of the box.
Does Google still show the old search results page design to Safari users? It did that for a long time.