Consider VS Code, software generally considered to be fast enough: every single interaction is handled by a dedicated, hand written, event handler which wherever possible directly modifies existing DOM nodes with the smallest amount of change possible.

This is miles from React. It's what SolidJS aims to do, but the state of the art here seems to be about equivalent to ASM vs Compiled C in 1980: an expert can get miles better performance by dropping down as far as possible in the stack themselves. Not to mention SolidJS forces you into their "lens" of JS, where variables are functions and functions are auto-invoked at the compilers will. And don't even think about refactoring an expression inside JSX to be outside of it or else you'll break all of reactivity. Unless you wrap it in another function, of course.