Computer Stats

  • Mac mini (Late 2014)
  • 2.8 GHz i5
  • 8 GB RAM
  • 10.13.5 High Sierra (upgraded from Sierra this week while debugging this issue)


I recently noticed that a certain tab in Chrome was using essentially 100% of a CPU core. The issue happens every time I am logged into the web app my company develops. There is an open web socket (with usually only heartbeat pings), but other than that the site is sitting idle so should not consume any (or very little) CPU.

I have logged into the webapp using Chrome on a recent MacBook, MacBook Air and MacBook Pro and none of the 3 exhibited the same behavior. I have logged into the webapp using Safari on this same machine and it also does not have the same issue. I have logged into another account/user on this machine and do have the same issue while using Chrome.

I have uninstalled/re-installed Chrome. Run a few system adware/malware programs and additionally upgraded to High Sierra and the issue still persists.

Additionally, I have opened the Chrome debugger and run a profiler, and it reports a normal 99.9% idle site. There is only one other site that I have observed to exhibit the same behavior since discovering the issue and that is the American Express account. Seeing that particular website exhibit the same behavior caused me to start thinking malware/badware...


Before logging into the web app, I opened Activity Monitor and took a screen shot of the process details:

Before Logging In

After logging in (and allowing the site to fully load, render, etc.), you can see the CPU has jumped to nearly 100% and the peculiar thing (which may be a clue?) is that the Unix System Calls jump up significantly:

After Logging In

I don't have any other potential smoking guns except for the Unix System Calls (which I have not observed spiking on any other processes since seeing it). I just would like to know what could potentially cause this spike, and how to go about the next steps of debugging the issue.

If there is potentially another issue that you feel I should look for, please share those as well.

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