The WebAssembly module is 1.6 - 1.8 MB brotli-compressed depending on the Wasm feature set. We're currently investigating ways to reduce this to around 1 MB. We further use streaming instantiation which means that the WebAssembly module will be compiled while downloading it. But still, it will hurt a bit more than a 40KB library.

Regarding multi-tab usage: Not today. The available filesystem apis make it difficult to implement this right now. We're looking into ways to make DuckDB-Wasm persistent but we can only read in this release.

On https://shell.duckdb.org/versus, we have a comparison with related libraries. The WASM bundles currently is 1.8 MB but it can be instantiated while it's streaming in.

The size probably makes it prohibitive to use DuckDB when your dataset is small and download size matters but we hope that future improvements in WebAssembly can get the size down.