Cursor Tracking Lag Caused by system_profiler

We’ve noticed problems with mouse cursor tracking, on Thunderbolt Macs attached to displays.

In the middle of moving the cursor with mouse or trackpad, the cursor jumps or skips making it difficult to control.

We tracked down the problem to background runs of system_profiler.  Specifically, when system_profiler queries the display for information.

Running system_profiler without flags or with the SPDisplaysDataType data type triggers the problem.

To reproduce the problem at its worst, run the following in Terminal on a Thunderbolt Mac attached to a display and attempt to use the tracking device:

while [ 1 ]; do system_profiler SPDisplaysDataType; done

Apple is aware of the issue, but has stated that this is expected behavior.

Many tools that rely on system_profiler trigger the issue including JAMF Casper Suite, Puppet, and Apple Remote Desktop.  These and other tools routinely inventory the Mac using system_profiler.

There is currently no workaround for getting display information such as Display serial number.  And the only way to avoid the trigger is to run system profiler with each data type excluding SPDisplaysDataType.

If you think Apple should address the issue, please let them know.

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