Had the same problem using Visual Studio Code while using Android Studio along with an Android Simulator in the background, and I run 8GB RAM and a CPU of 3.2GHz but when I returned to Notepad++ (I know its suicidal), to check if it is my problem or because of the IDEs, I typed in real time.
It is due to your processor as Visual Studio Code is not really recommended for “slow” CPUs. Personally I like it, although an IDE in the likes of Vim might suit you better.
Here is a link that might give some more hints:
https://github.com/Microsoft/vscode/issues/38409