I’ve also been using Elixir + Zed for the last couple months. Love it. And it’s so snappy. It’s the first editor I’ve found where ElixirLS doesn’t feel like it’s making my editor lag. Not sure what they do differently.
From what I gather it’s a combination of immutable data structures, light caching, and running the lsp/treesitter in background processes. The founder has a bunch of interesting interviews going deep into the mechanics if you’re interested!