There is no secret ingredient, writing a website, or anything really, without a framework is not wildly more difficult than using a framework.
Save for a few cases where all you really want to do is covered by the default configuration, you generally don't end up writing a lot less code with a framework. Worst case, you end up spending most of your time working around the framework.
What? This is absolutely untrue for anything that isn't a trivial v1 prototype. Complex applications have a lot of boilerplate, which is unavoidable with the baggage of HTML and CSS.
There's a reason people are obsessed with web frameworks. Writing vanilla HTML/CSS/JS for large or complex apps is an enormous pain.
React et al. won’t just be 10x slower, it will also use 5x the amount of code with 5x the complexity.
People are obsessed with web frameworks because it’s more fun to engineer frameworks than make products or ship applications. Applications are boooooring. But, most of the time, you’re just wasting your time with the framework.