There are a few tools online tools to improve how quickly the page loads and is usable.

Seems like a good tool for doing a first pass: https://web.dev/measure
This has some more React-specific optimisations: https://web.dev/react

Expected tweaks:

• Gzip compression
• Long caching of assets
• Optimisation of JPEG (+progressive)
• Use code spitting - https://serverless-stack.com/chapters/code-splitting-in-create-react-app.html