I really don't get a sense of what snowpack exactly does from their website but I found this blog post useful: https://blog.logrocket.com/snowpack-vs-webpack/
Snowpack: Run a module build script one time (or again when adding new NPM libraries) on project to generate some assets, but no re-bundling time between changes.
Parcel's incremental build is < 100ms, so I'm not sure how SnowPack feels any better for me.
"Snowpack treats bundling as a final, production-only build optimization. By bundling as the final step, you avoid mixing build logic and bundle logic in the same huge configuration file. Instead, your bundler gets already-built files and can focus solely on what it does best: bundling."