• VSCode Version: 1.20.0 (also occurs on 1.21 Insider)
• OS Version: Windows 10 Pro 16299

Steps to Reproduce:

1. Open a folder containing a repo with a lot of submodules (e.g. https://github.com/github/linguist, which contains 300 submodules in the vendors/grammars subdirectory). The submodules must be initialized and updated for this bug to manifest, so you must init and update submodules after cloning https://github.com/github/linguist from scratch.
2. Wait some seconds, or open the Git pane
3. VSCode spawns hundreds of Git subprocesses all at once, which effectively fork bombs my machine for several minutes, during which the entire computer (OS, VSCode, mouse cursor) is completely unresponsive.
   

Does this issue occur when all extensions are disabled?: Yes