insert mode --- inoremap <C-d> :deleteRight<CR> always delay. pls check the detail

Describe the bug
hello guys, I`m a vim user who came to VSCode not too long, when I want to map my vim key mapping as following, when normal mode into insert mode, it always need to take about 1 second for the map to take effect, if you trigger <C-d> as long as you going to insert mode, something strange will happen!!! .... this is the first point.

    "vim.insertModeKeyBindingsNonRecursive": [
        {
            "before": [
                "<c-d>",
            ],
            "commands": [
                "deleteRight",
            ],
        },

2. as the code show following, in normal mode, when I trigger v<C-e>, first it go to visual mode, and then will scroll down as native does....., and when you trigger <C-e> again, the cursor will move to the line end.. it is so strange.. Pls help, it will be highly appreciated if you could make it
   work as in native vim :).

 "vim.visualModeKeyBindingsNonRecursive": [
    {
            "before": [
                "<c-e>",
            ],
            "commands": [
                "cursorEnd",
            ],
        },
]

Expected behavior
I use <C-d>, <C-a>, <C-e>,<C-f>, <C-b> in vim inset mode like they are in emacs, but in normal mode <C-b>, <C-f> is the native vim way - scroff half screen.

Right now only <C-d>, and <C-e> is a little strange, and hard to work as I hope.

Environment (please complete the following information):
Ubuntu 18.04
Version: 1.39.2
Commit: 6ab598523be7a800d7f3eb4d92d7ab9a66069390
Date: 2019-10-15T15:33:40.634Z
Electron: 4.2.10
Chrome: 69.0.3497.128
Node.js: 10.11.0
V8: 6.9.427.31-electron.0
OS: Linux x64 4.15.0-58-generic

Start by reproducing the reported insert- and visual-mode mappings from the issue in the stated VS Code/Vim environment, focusing on the delay and the behavior. Trace the keybinding handling entry point and existing tests, if available; done means these mappings behave consistently with the described native Vim expectations without affecting the other listed controls.