LightAtom

Mac Internet Slow? Find What's Using Your Connection

Find out whether your Mac's slow internet is the connection, Wi-Fi, or an app quietly using bandwidth, and fix it.

The internet feels slow on your Mac: pages crawl, video buffers and calls stutter, sometimes while other devices seem fine.

  • Pages load slowly or stall.
  • Speed tests show much less than your plan.
  • Calls lag when something else is downloading.

Quick fix

Measure first. In Terminal, run:

networkQuality

It reports download and upload speed and responsiveness (RPM, round trips per minute). Low throughput points to Wi-Fi or the line; good throughput with low responsiveness points to bufferbloat. Then check which apps are using the network right now.

Why it happens

An app is uploading or downloading in the background (backups, cloud sync, updates).Most likely
Weak or crowded Wi-Fi.Most likely
Bufferbloat: latency spikes when the line is busy.Sometimes
A VPN routing traffic through a distant server.Sometimes
Slow DNS server.Rarely

Fixes

  1. Find the app using the bandwidth

    1. Activity Monitor › Network tab, sorted by Sent Bytes or Rcvd Bytes, shows totals per process.
    2. In Terminal, nettop -P shows live traffic per process (press q to quit); nettop -P -L 1 -J bytes_in,bytes_out prints one snapshot.
    3. Pause iCloud, Dropbox, Google Drive, Time Machine and app updates while you test.

  2. Test Wi-Fi vs the line

    1. Run networkQuality near the router and far from it, or over Ethernet. A big difference means Wi-Fi is the bottleneck.

  3. Fix bufferbloat

    1. Run the bufferbloat test. A grade of C or worse means enabling SQM/QoS on the router will help.

  4. Check the VPN and DNS

    1. Test with the VPN off or a nearer server.
    2. Use the DNS speed test and switch to a faster resolver if yours is slow.

Still not working?

If speeds are low on every device over Ethernet too, the line or the ISP is the bottleneck; contact them with your networkQuality or speed-test results at different times of day.

See it in the app

LightAtom's connections view shows each app's live download and upload rate, so the one eating your bandwidth stands out immediately.

Frequently asked questions

Why is my Mac's internet slow but my phone is fine?

Check whether an app on the Mac is using bandwidth (backups, sync, updates), and whether the Mac's Wi-Fi signal is weaker where it sits. A VPN on the Mac only is another common cause.

How do I test internet speed on a Mac?

Run networkQuality in Terminal. It measures download, upload and responsiveness using Apple's servers, with no website or app needed.

How do I see which app is using my internet on a Mac?

Activity Monitor's Network tab shows totals per process; nettop -P in Terminal shows live traffic. LightAtom shows live rates per app with the servers they connect to.

Related

LightAtom team

The people who build LightAtom, a network monitor for macOS.