Keystroke lag in TypeScript

[Cre3per]

Describe the bug
Noticeable keystroke lag when typing in TypeScript files.
Only observed when NativeScript is installed. I don't have issues with other TypeScript projects. Likely caused by many/large .d.ts files.

Ways to stop the lag

• Disable VSCodeVim
• Disable editor.quickSuggestions (This is my best workaround so far)
• Change the language mode to a non-TypeScript language

To Reproduce
Steps to reproduce the behavior:

1. In an empty directory

npm init -y
npm install "@nativescript/types"
touch tsconfig.json
echo '/// <reference path="./node_modules/@nativescript/types/index.d.ts" />' > references.d.ts

2. Open the project in vscode
3. Open index.ts
4. Wait for "Initializing JS/TS language features" in bottom bar to disappear (takes ~1 second)
5. Type "console"

Alternatively, after the file has been opened and js/ts initialized

1. Press ctrl+space to trigger auto-complete
2. Type (Will be delayed until auto-complete finished loading suggestions)

Expected behavior
Typing is smooth and snappy. There are no noticeable delays after pressing a key

Environment (please complete the following information):

• Extension (VsCodeVim) version: 1.21.10
• VSCode version: 1.63.2
• OS: 5.16.2-arch1-1 x86_64 GNU/Linux

All non-default extensions are disabled.

Additional context
Developer Tools Log while typing the letters "le" of "console" (handleKeyEvent() takes >100ms). The slower I type the earlier the slow keystroke occurs. The written word and letters don't matter.

[Extension Host] ModeHandler: debug: handling key=l.
console.ts:137 [Extension Host] Remapper: debug: trying to find matching remap. keys=l. mode=Insert. keybindings=insertModeKeyBindingsMap.
console.ts:137 [Extension Host] Transformer: debug: Adding Transformation {"type":"insertTextVSCode","text":"l","isMultiCursor":false}
console.ts:137 [Extension Host] Extension Startup: debug: Selections: ignoring intermediate selection change: [0, 6; 0, 6]
console.ts:137 [Extension Host] ModeHandler: debug: handleKeyEvent('l') took 211ms
console.ts:137 [Extension Host] ModeHandler: debug: handling key=e.
console.ts:137 [Extension Host] Remapper: debug: trying to find matching remap. keys=e. mode=Insert. keybindings=insertModeKeyBindingsMap.
console.ts:137 [Extension Host] Transformer: debug: Adding Transformation {"type":"insertTextVSCode","text":"e","isMultiCursor":false}
console.ts:137 [Extension Host] Extension Startup: debug: Selections: ignoring intermediate selection change: [0, 7; 0, 7]
console.ts:137 [Extension Host] ModeHandler: debug: handleKeyEvent('e') took 31ms

I have traced the lag down to execute.ts executeTransformations()

      case 'insertTextVSCode':
        const now = Number(new Date());
        await TextEditor.insert(vimState.editor, transformation.text);
        console.log(`insertion took ${Number(new Date()) - now}ms`);
        vimState.cursors[0] = Cursor.FromVSCodeSelection(vimState.editor.selection);
        break;

Thanks for the awesome extension, it has served me well so far!

[Cre3per]

Likely related to microsoft/vscode#65876

[Cre3per]

I have the same issue with the minimal extension shown by alex here microsoft/vscode#65876 (comment)

Removing

• await when calling TextEditor.insert
• The line vimState.cursors[0] = Cursor.FromVSCodeSelection(vimState.editor.selection); in execute.ts executeTransformations()

reduces the handleKeyEvent() duration to normal 5ms, but doesn't solve the issue. This hints that using a command other than default:type (If one exists) will not solve the issue.

My current guess is that default:type triggers "something" (Autocomplete) and awaits it.
If we don't await default:type, "something" will be awaited by another command later.

[Cre3per]

VSCode Neovim bypasses this issue by disposing its "type" command handler when entering insert mode. They register a keybind on "escape", "ctrl+[", and "ctrl+c" to return to normal mode and re-register the "type" handler.
While recording, they keep the "type" handler attached but don't use "default:type". I didn't see how they update the editor while recording. IIRC vimState.editor.edit(TextEdit.insert(/* ... */)) can be used to update the editor without triggering suggestions (Thus causing no lag).

I'm a vim newbie, I don't know if keystrokes in insert mode are needed for anything other than recording*. Maybe someone more experienced can get me up to speed.
Is there a reason why VSCodeVim can't behave like this?

Looking into these extensions has been pleasant so far. If I get confirmation that VSCodeVim could replicate VSCode Neovim's behavior, I'd like to try fixing VSCodeVim.

*UPDATE: ctrl+k and ctrl+v for digraphs and unicode. Might be doable with keybinds. The neovim extension doesn't support these.

[Arcitec]

Looks like a good investigation. Thanks @Cre3per. I decided to switch to the NeoVim extension for the reasons outlined by you and summarized by me here:

#8115 (comment)

It's also a more complete Vim implementation because it's literally Vim, not an emulation.

If the extreme slowdown in VSCode/VSCodeVim is ever solved, I'll probably switch back since the idea of having Vim entirely implemented in JavaScript appeals to me.

[Ahmad-Alkaf]

Ways to stop the lag

• Disable VSCodeVim
• Disable editor.quickSuggestions (This is my best workaround so far)
• Change the language mode to a non-TypeScript language

@Cre3per I noticed also delaying the quick suggestions pop-up editor.quickSuggestionsDelay to about 600 stopped the lagging