I don't think you need to run npm start so often. I've created my project via create-react-app which comes with Hot Module Reloading or HMR(restarts the server on any saved edit) in-built.
Starting a new React server multiple times can also be problematic as every time it will run on a different port. If you're integrating an API that has CORS set up for a particular port, it won't work on other instances.
What to do?
- Create your application using
create-react-app(cra) or add HMR using some library if you don't want to use cra. Here is a tutorial for that (haven't tested it).
- Always keep a single dev server running. It will automatically reload on code change.
- Stop the server by
Ctrl + C when you don't want to use it.