VSCodeVim makes quick suggestions slow (includes video demonstration)

Describe the bug

VSCodeVim is causing VSCode to lag behind keyboard input for up to a second when the quick suggestions would show. The lag is excruciating enough that I have disabled all quick suggestions, which is the only workaround I know of that allows me to keep using VSCodeVim.

🎞Complete reproduction video
https://drive.google.com/open?id=1IMFV1Uetsecz0adiB_2kQ2nQf5i3Fveg

To Reproduce
Steps to reproduce the behavior:

• Start VSCode with no extensions enabled
• Ensure that you have the following in your settings.json:

    "editor.quickSuggestions": {
        "other": true,
        "comments": true,
        "strings": true
    }

• Create a TypeScript project
• Install the aws-sdk package in the project (it has a lot of type defs)
• Create a .ts file in the project
• Type import AWS from 'aws-sdk' into the file.
• Below that, begin typing const s3 = new AWS.S3()
  • you should notice no lag in keyboard input while typing
• Enable VSCodeVim
• Backspace and retype the AWS.S3 portion of the line
  • you should notice significantly more lag in keyboard input
  • try a few times if you don't immediately notice lag
• Now disable quick suggestions in your settings.json:

    "editor.quickSuggestions": {
        "other": false,
        "comments": false,
        "strings": false
    }

• Backspace and retype the AWS.S3 portion of the line again
  • now there's no more lag

Expected behavior
VSCodeVim causes no lag in keyboard responsiveness, even when quick suggestions are turned on.

Environment (please complete the following information):

• Extension (VsCodeVim) version: 1.13.0
• VSCode version: 1.40.0
• OS: macOS 10.15.1 (19B88)

Start by reproducing the issue with the settings.json quickSuggestions configuration, the TypeScript project, and the aws-sdk package described above. Compare typing AWS.S3 with VSCodeVim enabled and disabled, then verify that quick suggestions remain enabled without keyboard lag when the issue is fixed.