They briefly touched on what makes Svelte different but for some reason didn’t highlight it as the main takeaway.
When Svelte builds your app, it’s fully aware of what components will need to update when data changes, and so it can wire up those precise dependencies statically. Then when data changes at runtime, instead of needing to diff the new state against the old state, components are updated in the way that was prescribed at build time, which is maximally efficient (as long as Svelte’s compiler is reasonably smart).
When Svelte builds your app, it’s fully aware of what components will need to update when data changes, and so it can wire up those precise dependencies statically. Then when data changes at runtime, instead of needing to diff the new state against the old state, components are updated in the way that was prescribed at build time, which is maximally efficient (as long as Svelte’s compiler is reasonably smart).