I initially set out to write a deep dive into the source code and output code of React and Svelte. However, I realized that the post was becoming overly boring and lengthy, so here is a summary of the key takeaways I found out:

• Svelte is essentially a modern React with no virtual DOM and some compile-time optimizations
• Svelte 5 runes reduces compile-time magic: the framework now mostly transpiles component files into pure functions, renames stuff like $effect -> user_effect/template_effect, and uses set and get for $state
• React, by contrast, only compiles JSX into JavaScript
• React’s larger size is likely due to its age and popularity. Virtual DOM doesn’t help either
• I couldn’t figure out how Svelte achieves its impressive compression rates