It's not just db queries though.. it's also things like 3rd party API calls (S3 for example). Basically anything where you're blocked waiting for a response yo

It's not just db queries though.. it's also things like 3rd party API calls (S3 for example). Basically anything where you're blocked waiting for a response you could be busy doing something else. Synchronous APIs are kind of wasteful in a lot of cases. Node.js does a good job of this by using async APIs. It's a tradeoff. But the extra complexity can be worth it if it means your pages load 2x faster.