I had similar problems as well (SECOND ACTION - in my answer should solve your problem). My system was suddenly "laggy" as well, with no prior sign of significant damage. My windows self-restarted on its own, attempting to fix the problem but still didn't resolve it. When I use the command:
code .
in the comand line to open a folder in visual studio code (vscode) editor, it opens multiple instances of windows tab. Below is how I tackled the two problems:
Two things (Actions);
FIRST ACTION: (targeted: Laggy windows OS)
I used the command prompt(in Admin mode) to run the command: ”
sfc /scannow
This action fixed some corrupt system file and solved the laggy nature. I noticed significant improvement, possibly restoring it to previous performance level.
Check the Microsoft docs for more info.
SECOND ACTION: (Visual Studio Code opens multiple instances - should answer your question)
Open vscode editor, go to the setting and paste this in the search bar:
"workbench.editor.enablePreview": false
If you have this option marked, you should unmark it or set it to false depending on the interface you are presented and interacting with. This should stop vscode from running multiple instances and hopefully resolve your problem.