UI freezes for ~10 seconds on :! external commands on Windows

Oni Version: September 15 2019 Build 64 bit Windows exe

Neovim Version (Linux only): Operating System: Windows 7 64-bit

Issue: Running :! to perform an external command freezes UI for about 10 seconds before displaying results (e.g., .exe files on Windows)

Expected behavior: Much quicker, < 1 second max response time.

Actual behavior: ~10 second freeze of UI before showing results

Steps to reproduce:

1. Open Oni2.exe
2. Hit :!