Server CPU usage is extremely high when using GUI, even when no players are connected

Since Minecraft 1.8 (or maybe earlier), I've been starting my home Minecraft Server with the GUI so that I can see which of my kids are connected. I start the server from a BASH terminal using:

java -Xmx1024M -Xms1024M -jar minecraft_server.jar

(Java SE version is 1.8.0_91)

When I upgraded to Minecraft Server 1.10, I noticed that the CPU usage was always high, even when no players are connected.

To compare, I tried running the exact same world using both the GUI and NOGUI and noting the CPU usage. Here are my results:

Minecraft Server 1.8.4

• nogui = hovers between 0.5% and 6% CPU
• with GUI = hovers between 49% and 80% CPU

Minecraft Server 1.9.4

• nogui = hovers between 0.8% and 8% CPU
• with GUI = hovers between 41% and 80% CPU

Minecraft Server 1.10.2

• nogui = hovers between 0.8% and 6% CPU
• with GUI = hovers between 48% and 95% CPU

Clearly the GUI is using far more CPU than the "nogui" option, but why? It's not exactly rendering any fancy graphics and there doesn't seem to be a reason for the simple GUI to need so much CPU compared to "nogui". Does showing the "Memory use" and the "Avg tick" really need so much CPU to be consumed?