Tune page load performance

[damianmoore]

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