Client js size Bundled File Size File Size build/bundle.js 13K build/bundle.min.js 6.5K build/bundle.min.js.gz 2.3K Source Files Size File Size client/index.js 4.2K client/jsx/dom.js 6.9K client/ws/ws-lite.js 2.5K client/ws/ws-config.js 280B WebSocket Client Size Comparison Name bundled + minified + gzipped ws-native 1.0K 0.4K 0.3K ws-lite 2.3K 0.9K 0.5K primus.js 98.9K 32.5K 10.7K socket.io.js 104K 40.8K 12.4K Details of ws-* refers to client/ws/readme.md WebSocket Client Way to get websocket client file primus.js fs.writeFileSync('primus.js', primus.library()) socket.io.js wget $origin/socket.io/socket.io.js Size Type Command bundled of ws-{native,lite} npx esbuild $file --bundle | pv > /dev/null bundled of {primus,socket.io}.js cat $file | pv > /dev/null + minified npx esbuild $file --bundle --minify | pv > /dev/null + gzipped npx esbuild $file --bundle --minify | gzip | pv > /dev/null Reference source: https://bundlephobia.com/ Network Download Speed (kB/s) 2g edge 30 emerging 3g 50