fix-visual-stability/environment/skills/react-best-practices/rules/async-parallel.md

metadata

title: Promise.all() for Independent Operations
impact: CRITICAL
impactDescription: 2-10× improvement
tags: async, parallelization, promises, waterfalls

Promise.all() for Independent Operations

When async operations have no interdependencies, execute them concurrently using Promise.all().

Incorrect (sequential execution, 3 round trips):

const user = await fetchUser()
const posts = await fetchPosts()
const comments = await fetchComments()

Correct (parallel execution, 1 round trip):

const [user, posts, comments] = await Promise.all([
  fetchUser(),
  fetchPosts(),
  fetchComments()
])