TechPrufer
Get started
Vercel
Vercel logoVercel · Feature trail

WebStreams Performance Optimization

3 posts · Jun 2023 – Feb 2026

What this trail covers

Vercel has developed a library called `fast-webstreams` that reimplements the WHATWG `ReadableStream`, `WritableStream`, and `TransformStream` APIs using Node.js streams internally. This library significantly improves performance for common operations like piping between streams, chunk-by-chunk reading, and handling React Server Component byte streams. The library aims to reduce Promise and object allocation overhead, leading to substantial speedups in server-side rendering and data processing. This work is being contributed upstream to Node.js.

All Vercel trails
  1. We Ralph Wiggumed WebStreams to make them 10x fasterThis post details the development of `fast-webstreams`, a library that reimplements WHATWG Streams using Node.js streams internally. It introduces optimizations for piping between streams (zero Promises per chunk, ~10x faster), chunk-by-chunk reading (synchronous resolution, ~3.7x faster), React Flight patterns (~14.6x faster), and fetch response bodies (~3.2x faster). The library passes 1100/1116 Web Platform Tests and is being deployed incrementally at Vercel, with contributions made upstream to Node.js.
  2. How streaming helps build faster web applicationsThis post details how the Next.js App Router utilizes streaming to improve web application performance. It explains how streaming allows for progressive UI delivery from server to client, preventing slow data sources from blocking initial UI display and enabling parallel loading of other assets. The post highlights the benefits of colocating compute next to data origins and introduces Partial Prerendering as a technique to generate a static shell for faster initial loading. It also discusses how streaming is applied in AI applications and LLMs to provide a better user experience by displaying responses as they are generated.
  3. An Introduction to Streaming on the WebThis post provides a comprehensive introduction to Web Streams API, explaining its core concepts like ReadableStream, WritableStream, and TransformStream. It details how chunks are handled, the importance of managing backpressure through flow control mechanisms, and the practical application of Web Streams with the Fetch API. It also touches upon Server-Sent Events (SSE) as a related technology for real-time updates.