Among web component frameworks, Svelte stands out by moving reactivity out of the browser and into the compiler. Instead of optimizing DOM updates by using a virtual DOM and browser optimization tricks, Svelte compiles your code into vanilla framework-less JavaScript code that surgically updates the DOM directly. In addition to the run-time performance benefits, this also allows Svelte to optimize the amount of code the browser has to download without sacrificing features for developers; moreover, it's proven to be performant and battery-friendly for mobile web applications as less code has to execute in the browser itself. Performance benefits aside, our teams have appreciated its friendly learning curve and the maintenance benefits that come from writing less code. Svelte itself is only the component framework, but SvelteKit adds features to build full web applications.
We continue to see new front-end JavaScript frameworks, and Svelte stands out as a promising new component framework. Unlike other frameworks that leverage the virtual DOM, Svelte compiles your code into vanilla framework-less JavaScript code that surgically updates the DOM directly. However, it's only a component framework; if you're planning to build feature-rich applications, consider assessing Sapper together with Svelte.