require with slash makes IntelliSense extremely unresponsive

[octref]

TypeScript Version: 2.6.1-insiders.20171019

OS: macOS 10.12.6

Code

• Use https://github.com/Microsoft/vscode-generator-code to generate a JavaScript VS Code extension

• npm install sass.js

• Add a file scss.js

  //@ts-check
  const compile = require('sass.js/dist/sass.node')
  
  compile('test.scss', { style: compile.Sass.style.compressed }, (res) => {
    console.log(res.text);
  })

Expected behavior: IntelliSense still works

Actual behavior: IntelliSense in any of the js files in the project takes 5 second to load

Zipped workspace (no node_modules, install them before trying)
matb.zip

/cc @mjbvz

[mjbvz]

Duplicate of #19458