Which command line parameters are passed to QEMU? Is your system able to use KVM (e.g. did you enable virtualization support in your BIOS)?
** Changed in: qemu Status: Confirmed => Incomplete -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1734810 Title: Windows guest virtual PC running abnormally slow Status in Boxes: New Status in KVM: New Status in libvirt: New Status in QEMU: Incomplete Status in spice related packages: Confirmed Status in gnome-boxes package in Ubuntu: Confirmed Bug description: Guest systems running Windows 10 in a virtualized environment run unacceptably slow, with no option in Boxes to offer the virtual machine more (or less) cores from my physical CPU. ProblemType: Bug DistroRelease: Ubuntu 17.10 Package: gnome-boxes 3.26.1-1 ProcVersionSignature: Ubuntu 4.13.0-17.20-lowlatency 4.13.8 Uname: Linux 4.13.0-17-lowlatency x86_64 ApportVersion: 2.20.7-0ubuntu3.5 Architecture: amd64 CurrentDesktop: ubuntu:GNOME Date: Tue Nov 28 00:37:11 2017 ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: gnome-boxes UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/gnome-boxes/+bug/1734810/+subscriptions