hrsh7th / slow-lsp-demo

slow-lsp-demo

In the past time, the neovim builtin-lsp and Lua based completion plugin slows down when using the old typescript-language-server.

This problem was caused by the following reasons...

1. The previous version of typescript-language-server behavior

The previous version of typescript-language-server returns toooooo many completion items.

-> Now, typescript-language-server uses isIncomplete=true and the payload is small as enough.

2. The previous version of nvim built-in lsp was using vim.fn.json_decode to parse LSP payloads.

It may take a time near 100ms if the payload toooo large.

-> Now, nvim built-in lsp uses cjson as the JSON parser. It quit faster than old one.

3. The previous version of nvim built-in lsp convert vim.NIL as nil via recursive processing.

It may take a time near 100ms if the payload toooo large.

-> Now, nvim built-in lsp converts vim.NIL to nil when parsing that is avoiding extra recursive processing.

NOTE: The completion plugin was the slowness reason too (but it isn't the core reason).

How can I reproduce the slowness with this repo?

1. Downgrade the nvim.
2. Downgrade the typescript-language-server as 0.4.0
3. Run npm install
4. Invoke completion with <|> on src/index.ts