After updating QEMU to 1214d55d1c41fbab3a9973a05085b8760647e411, I reinstalled Windows XP and the host CPU usage at idle was normal. My guess is that I picked a bad commit to reinstall Windows XP.
I tried using "-smp 4". Windows XP started up to a black screen. When I restarted the problem with high CPU usage at idle was back. I did not use the "-smp 4" option after restarting. When I first specified the '-smp 4' option I saw Windows install something then have the computer restarted. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1914667 Title: High cpu usage when guest is idle on qemu-system-i386 Status in QEMU: New Bug description: When running Windows XP in qemu-system-i386, the cpu usage of QEMU is about 100% even when the guest CPU usage is close to 2%. The host cpu usage should be low when the guest cpu usage is low. Command: qemu-system-i386 -hda <Windows XP HD image> Using this command also shows around 100% host CPU usage: qemu-system-i386 -m 700 -hda <Windows XP HD image> -usb -device usb-audio -net nic,model=rtl8139 -net user -hdb mountable.img -soundhw pcspk Using the Penryn CPU option also saw this problem: qemu-system-i386 -hda <Windows XP HD image> -m 700 -cpu Penryn-v1 Using "-cpu pentium2" saw the same high host cpu usage. My Info: M1 MacBook Air Mac OS 11.1 qemu-system-i386 version 5.2 (1ba089f2255bfdb071be3ce6ac6c3069e8012179) Windows XP SP3 Build 2600 To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1914667/+subscriptions