I was kinda surprised by this performance focused update, I have not had any performance issues whatsoever, even in big documents.
For this reason I can not use Sketch. It's just painfully slow compared to Designer (and Figma). When everything is "sticky" it really messes with my productivity.
Still, it churns and grinds to a shocking degree sometimes. In your experience, Figma is faster? That’s good to know, as we’re on Sketch at work, but consider other options.
Btw you can import Sketch files in Figma, so you can quite easily compare the two.
As a side note: I also really like the Figma design, auto layout is a game changer imo, component variants are also very nicely done. For UI it's really good, makes me very productive.
(For graphics I do still prefer Affinity Designer)