Navigation unresponsive on large files

Describe the bug
Hi, I noticed that when I open a large file (I have a JSON lines file that contains over 650k lines and is close to 900MB in size) the extension makes VSCode unresponsive to navigation and editing. I cannot move caret with h/j/k/l or arrow keys and I cannot toggle insert mode on. The problem goes away when I disable the extension.

I checked the open issues but I saw only issues related to slowness when opening large files but even larger files makes the extension unusable totally. Is this a known issue and is there a workaround?

To Reproduce
Steps to reproduce the behavior:

1. Open a large file
2. Try to navigate or switch to insert mode by pressing i
3. VSCode/vim-extension seems to be unresponsive

Expected behavior
Navigation and editing the file would work.

Environment (please complete the following information):

• Extension (VsCodeVim) version: 1.20.2
• VSCode version: 1.55.2
• OS: macOS Big Sur 11.3.1

Reproduce the issue in VS Code with a roughly 650k-line, 900MB JSON lines file using the Vim extension, then test caret movement, arrow keys, and insert mode. Compare behavior with the extension disabled and verify that navigation and editing remain responsive when the extension is enabled.