Observations on CPU Usage

I’ve read numerous reports that cpu usage is high and that computers are running hot. So is mine. But I’ve finally been able to pinpoint under which conditions it happens.

The problem with very high cpu usage only occurs on the Core computer and it only occurs when in fullscreen mode, especially in the queue or screensaver views. Roon in fullscreen on the Remote iMac usually uses about 20% cpu, but never hits 100% like on the Core. If I minimize Roon to the dock on the Core (Mac mini, late 2012, 8GB RAM, OS X Yosemite 10.10.3), cpu usage immediately drops to below 10%. If I maximize Roon again, it might not hit 100% usage immediately, but eventually I’ll hear some static pops in the music and checking the Activity Monitor, cpu usage is at 100%.

The Core computer is connected to the TV via HDMI and to the DAC via USB and I usually run it headless via the Remote computer and I don’t experience these problems. It’s when I have the TV on and have Roon in screensaver or queue mode that I start to run into these problems.

This is what the Activity Monitor looks like streaming a lossless TIDAL stream with Roon minimized to the dock:

This is the Activity Monitor streaming the same album, but in fullscreen, screensaver mode:

The problem is worse if I’m playing local lossless files from the hard drive of the Core computer (ALAC, 16-bit, 44.1kHz) under the same conditions:

That flat gap you see in the CPU LOAD graph is when I minimized Roon to the dock. Those three screen shots were taken within minutes of each other. Of course I don’t want to run Roon minimized to the dock, it’s just too damn good-looking for that.


I too have noticed that sometimes I get a high (>30%) CPU usage even when Roon is idle, not playing music or scanning folders.
And indeed, when I minimize Roon the CPU usage drops immediately. When the window returns to focus, the high usage returns.
I’m on Windows.