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What is nsurlsessiond on Mac? Why it uses so much CPU, and how to fix it

Updated · 2 min read · by

Quick answer

nsurlsessiond is the macOS service that handles background downloads and uploads for apps and system services. It's busy when something big is transferring. Short spikes are normal. If it stays high, something is keeping it busy, and the steps below find and fix it.

What is nsurlsessiond?

nsurlsessiond does downloads and uploads on behalf of other apps and services, so they can continue even when the app that asked isn't open. iCloud, the App Store, software updates, Photos, podcasts and many third-party apps use it.

Because the transfer belongs to another app, nsurlsessiond shows the network and CPU usage instead.

Why is nsurlsessiond using so much CPU?

How to fix high nsurlsessiond CPU usage

  1. Confirm it in Activity Monitor. Press ⌘ Space, type Activity Monitor, open the CPU tab and sort by % CPU. Watch nsurlsessiond for a minute: short spikes are normal, only steady high usage needs fixing.
  2. Check the Network tab in Activity Monitor: Sent Bytes and Rcvd Bytes show how much it's moving.
  3. Check for updates in progress in System Settings › General › Software Update and in the App Store.
  4. Look at iCloud syncs (iCloud Drive in Finder, or Photos) for a big transfer.
  5. Let it finish on a good connection, or restart if it seems stuck.

More help: Why is my Mac's battery draining fast?

Questions people ask

What is nsurlsessiond on a Mac?

nsurlsessiond is the macOS service that handles background downloads and uploads for apps and system services. It's busy when something big is transferring.

Can I quit nsurlsessiond?

It restarts automatically and resumes the transfers. Let them finish or pause the app that started them.

Is nsurlsessiond a virus?

Yes. nsurlsessiond is part of macOS.