High CPU use by system interrupts when Mathematica runs in Windows 10

Questions
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I’m wondering why system interrupts shows a constant high (relative to other processes) CPU use of between about 1.8% - 3% when Mathematica runs. The increase in CPU use occurs with just a blank notebook. I’m using Windows 10 64 bit. When I exit Mathematica, the CPU used by system interrupts drops to about 0.75% - 0.9%, which is the typical background level. This increase has the effect of keeping the fan in my notebook always on, which is quite annoying.