Don't worry use your desktop experience as your benchmark, if your mouse is smooth w/o any jitter while background apps are loading and your sound is fine - your system is responsive enough. Play games for a few hours. My Latency Mon numbers would say otherwise, but I can play many games w/o any stutter, I haven't played one that did. What I learned a few months late is that you don't need a lot of extra stuff with libvirtd for a smooth overall desktop experience.
So start simple with your configuration.
The more I played around with the CPU configuration, the more degraded my performance became. I learned that by just installing win10 using a basic native qemu setup and using a simple XML and adding what I see from forums, but one line at a time - to troubleshoot.
So here I am sharing mine. I borrowed some CPU config lines from Symon's XML. Not all of them worked for me because as I'm using qemu 4.0.0
<domain type="kvm">
<name>win10</name>
<uuid>fa7c22d6-89fa-4c7c-9d4f-86471b96e36f</uuid>
<metadata>
<libosinfo:libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0">
<libosinfo:os id="http://microsoft.com/win/10"/>
</libosinfo:libosinfo>
</metadata>
<memory unit="KiB">33554432</memory>
<currentMemory unit="KiB">33554432</currentMemory>
<vcpu placement="static">24</vcpu>
<os>
<type arch="x86_64" machine="pc-q35-4.0">hvm</type>
<loader readonly="yes" type="pflash">/mnt/data/firmware/OVMF_CODE.fd</loader>
<nvram>/mnt/data/firmware/OVMF_VARS_win02.fd</nvram>
</os>
<features>
<acpi/>
<apic/>
<hyperv>
<relaxed state="on"/>
<vapic state="on"/>
<spinlocks state="on" retries="8191"/>
<vendor_id state="on" value="132271374ch"/>
</hyperv>
<kvm>
<hidden state="on"/>
</kvm>
<ioapic driver="kvm"/>
</features>
<cpu mode="host-passthrough" check="full">
<topology sockets="1" cores="12" threads="2"/>
<cache mode="passthrough"/>
<feature policy="require" name="topoext"/>
<feature policy="disable" name="ibpb"/>
<feature policy="disable" name="virt-ssbd"/>
</cpu>
<clock offset="localtime">
<timer name="rtc" tickpolicy="catchup"/>
<timer name="pit" tickpolicy="delay"/>
<timer name="hpet" present="no"/>
<timer name="hypervclock" present="yes"/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<pm>
<suspend-to-mem enabled="no"/>
<suspend-to-disk enabled="no"/>
</pm>
<devices>
<emulator>/usr/bin/qemu-system-x86_64</emulator>
<disk type="file" device="disk">
<driver name="qemu" type="raw"/>
<source file="/mnt/data/Windows/Win10x-boot.img"/>
<target dev="vda" bus="virtio"/>
<boot order="1"/>
<address type="pci" domain="0x0000" bus="0x0c" slot="0x00" function="0x0"/>
</disk>
<disk type="file" device="disk">
<driver name="qemu" type="raw"/>
<source file="/mnt/data/Windows/WinDisk.img"/>
<target dev="vdb" bus="virtio"/>
<boot order="2"/>
<address type="pci" domain="0x0000" bus="0x0d" slot="0x00" function="0x0"/>
</disk>
<disk type="file" device="disk">
<driver name="qemu" type="raw"/>
<source file="/home/me/Downloads/virtio-win-0.1.171.iso"/>
<target dev="vdc" bus="virtio"/>
<address type="pci" domain="0x0000" bus="0x0e" slot="0x00" function="0x0"/>
</disk>
<disk type="file" device="disk">
<driver name="qemu" type="raw"/>
<source file="/mnt/data/Windows/Win10_1903_V1_English_x64.iso"/>
<target dev="vdd" bus="virtio"/>
<address type="pci" domain="0x0000" bus="0x0f" slot="0x00" function="0x0"/>
</disk>
<controller type="usb" index="0" model="qemu-xhci" ports="15">
<address type="pci" domain="0x0000" bus="0x02" slot="0x00" function="0x0"/>
</controller>
<controller type="sata" index="0">
<address type="pci" domain="0x0000" bus="0x00" slot="0x1f" function="0x2"/>
</controller>
<controller type="pci" index="0" model="pcie-root"/>
<controller type="pci" index="1" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="1" port="0x10"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x0" multifunction="on"/>
</controller>
<controller type="pci" index="2" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="2" port="0x11"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x1"/>
</controller>
<controller type="pci" index="3" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="3" port="0x12"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x2"/>
</controller>
<controller type="pci" index="4" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="4" port="0x13"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x3"/>
</controller>
<controller type="pci" index="5" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="5" port="0x14"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x4"/>
</controller>
<controller type="pci" index="6" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="6" port="0x15"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x5"/>
</controller>
<controller type="pci" index="7" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="7" port="0x16"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x6"/>
</controller>
<controller type="pci" index="8" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="8" port="0x17"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x02" function="0x7"/>
</controller>
<controller type="pci" index="9" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="9" port="0x18"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x0" multifunction="on"/>
</controller>
<controller type="pci" index="10" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="10" port="0x19"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x1"/>
</controller>
<controller type="pci" index="11" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="11" port="0x1a"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x2"/>
</controller>
<controller type="pci" index="12" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="12" port="0x1b"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x3"/>
</controller>
<controller type="pci" index="13" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="13" port="0x1c"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x4"/>
</controller>
<controller type="pci" index="14" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="14" port="0x1d"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x5"/>
</controller>
<controller type="pci" index="15" model="pcie-root-port">
<model name="pcie-root-port"/>
<target chassis="15" port="0x1e"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x03" function="0x6"/>
</controller>
<controller type="virtio-serial" index="0">
<address type="pci" domain="0x0000" bus="0x03" slot="0x00" function="0x0"/>
</controller>
<controller type="scsi" index="0" model="virtio-scsi">
<address type="pci" domain="0x0000" bus="0x0b" slot="0x00" function="0x0"/>
</controller>
<interface type="direct">
<mac address="52:54:00:ce:4e:e5"/>
<source dev="enp5s0" mode="bridge"/>
<model type="e1000e"/>
<address type="pci" domain="0x0000" bus="0x05" slot="0x00" function="0x0"/>
</interface>
<input type="mouse" bus="ps2"/>
<input type="keyboard" bus="ps2"/>
<graphics type="spice" autoport="yes">
<listen type="address"/>
<image compression="off"/>
<gl enable="no"/>
</graphics>
<video>
<model type="cirrus" vram="16384" heads="1" primary="yes"/>
<address type="pci" domain="0x0000" bus="0x00" slot="0x01" function="0x0"/>
</video>
<hostdev mode="subsystem" type="pci" managed="yes">
<source>
<address domain="0x0000" bus="0x41" slot="0x00" function="0x0"/>
</source>
<rom bar="on"/>
<address type="pci" domain="0x0000" bus="0x01" slot="0x00" function="0x0"/>
</hostdev>
<hostdev mode="subsystem" type="pci" managed="yes">
<source>
<address domain="0x0000" bus="0x41" slot="0x00" function="0x1"/>
</source>
<address type="pci" domain="0x0000" bus="0x06" slot="0x00" function="0x0"/>
</hostdev>
<hostdev mode="subsystem" type="pci" managed="yes">
<source>
<address domain="0x0000" bus="0x41" slot="0x00" function="0x2"/>
</source>
<address type="pci" domain="0x0000" bus="0x07" slot="0x00" function="0x0"/>
</hostdev>
<hostdev mode="subsystem" type="pci" managed="yes">
<source>
<address domain="0x0000" bus="0x41" slot="0x00" function="0x3"/>
</source>
<address type="pci" domain="0x0000" bus="0x08" slot="0x00" function="0x0"/>
</hostdev>
<hostdev mode="subsystem" type="usb" managed="yes">
<source>
<vendor id="0x1b1c"/>
<product id="0x0a14"/>
</source>
<address type="usb" bus="0" port="4"/>
</hostdev>
<hostdev mode="subsystem" type="usb" managed="yes">
<source>
<vendor id="0x046d"/>
<product id="0xc332"/>
</source>
<address type="usb" bus="0" port="8"/>
</hostdev>
<hostdev mode="subsystem" type="usb" managed="yes">
<source>
<vendor id="0x046d"/>
<product id="0xc333"/>
</source>
<address type="usb" bus="0" port="9"/>
</hostdev>
<hostdev mode="subsystem" type="usb" managed="yes">
<source>
<vendor id="0x045e"/>
<product id="0x02ea"/>
</source>
<address type="usb" bus="0" port="1"/>
</hostdev>
<redirdev bus="usb" type="spicevmc">
<address type="usb" bus="0" port="2"/>
</redirdev>
<redirdev bus="usb" type="spicevmc">
<address type="usb" bus="0" port="3"/>
</redirdev>
<memballoon model="virtio">
<address type="pci" domain="0x0000" bus="0x04" slot="0x00" function="0x0"/>
</memballoon>
</devices>
</domain>
