This extension adds styles to turn the tab bar into a vertical tab bar. This is only done when the standard sidebar is hidden, so it doesn't consume to much space. This makes it much easier to deal with large lists of files:
Install and activate VS Code Custom CSS Plugin
Add the following to your user settings. Make sure you substitute your home folder for the custom CSS path below.
{
"vscode_custom_css.imports": [
"file:///Users/PATH_TO_YOUR_HOME_FOLDER/.vscode/extensions/pzuraq.vertical-tab-bar-1.0.0/styles.css"
]
}