I'm going to tell you a secret. If you are building an SPA, you can take advantage of optimisations that give you epic scalability, with super low latencies at a fraction of the cost. To understand the secret, I'll need to teach you a few things such as the actors involved in transferring data from your server to the browser; and about the ancient technology called 'serverless' which you might be surprised to learn is something you've already been using for years. By the end, you'll know the secret of how to architect an SPA for scale without breaking the bank.