The loading spinners happen when data is being fetched from the database. The app itself is downloaded upon initial load and anything from the database will trigger a loading spinner as it's being fetched.
Spinners make it look like the app is taking ages to load data, even if it's not. If you delay showing the spinner until around a second of loading, it makes things feel a lot faster.
The user doesn't need to always know when the app is loading data until there's a significant pause and they need to know stuff is happening.
Is the time the spinners run determined by the time the server needs to deliver the data? Would they go away when you put the site behind a CDN that delivers the data faster?
> Is the time the spinners run determined by the time the server needs to deliver the data?
Basically. But you can also render your react app or vue on the server and then have client side rendering take over once the page is loaded. This is perhaps the ideal case but it's more complicated and takes some work to set up (I haven't actually done it).