Solid author here. Hmm don't see this on Firefox on Windows or on my Macbook air. From what you are describing it's probably the REPL acting up. I wouldn't use that as a measure of performance.
SolidJS is a UI library, that is basically a reactive state library first, renderer second. It happens to look like React by choice, since it chooses JSX for its flexible composability and React Hooks resemble reactive primitives. Cliff notes are reactivity is independent of components. Components are just functions that run once and wire up granular updates. Then only the things that change ever re-run.