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JavaScript Promise.all vs sequential await: 0.10 s vs 1.01 s
Is Promise.all faster than awaiting in a loop?
Ten independent 100 ms calls took 1.01 s when awaited one after another and 0.10 s with Promise.all in Node 22.
Results
| sequential awaits | 1.01 s |
|---|---|
| Promise.all | 0.10 s |
How it was measured
10 simulated 100 ms calls.
await Promise.all(ids.map(fetchUser));Why
Promise.all starts every call first and then waits once.
When this does not apply
Only for independent calls; limit concurrency for large lists.
Environment
MacBook Air (Apple silicon, 8 cores), macOS, Node 22. Measured 2026-10-12.
Source: shorts/demo-ticket/w3/promises.mjs in my content-engine repository. Treat any single run as a direction; re-run it on your hardware.
By Josué Barros, senior software engineer (full-stack, data and AI).