It can be done, it is genuinely useful for testing, and it will never feel like a real PC. This page explains the double tax a nested Windows guest pays, the driver step that removes half the pain, and exactly which Windows jobs belong in a nest.
Windows is the stress test of any nested lab: a heavy, graphical, always-busy operating system asked to run on a hypervisor inside a hypervisor. People try it for good reasons — testing an install, checking a GPO, rehearsing a deployment — and then judge the whole nested idea by how a Windows desktop feels. That judgement needs context. Windows in a nest pays a double tax, starts life with emulated hardware that makes it worse, and still ends up perfectly serviceable for the jobs it is actually for. Here is the full picture.
Every privileged operation a nested Windows guest performs is translated by Proxmox's KVM, and the result is then translated again by ESXi. A desktop OS performs these operations constantly — window rendering, disk indexing, background services, updates — so Windows shows the tax more honestly than a quiet Linux server does. Boot times stretch, installs crawl, and the desktop has a faint but permanent heaviness. None of this means failure. It means the right question is never "is it fast?" but "is it fast enough to test what I came to test?" — and for installs, policies and procedures, it usually is.
The single biggest controllable factor. Proxmox offers emulated hardware (IDE disk, e1000 network) that Windows recognises instantly — and that performs like hardware from another decade, through two hypervisors. The fix is the virtio-win driver ISO: attach it as a second CD drive at creation, and during Windows setup, when the installer "cannot see" the VirtIO disk, load the storage driver from that ISO. After installation, run the full virtio-win installer inside Windows to add the network, balloon and guest-agent drivers.
Set the VM's CPU type to host, so Windows sees the real processor features instead of an emulated museum piece — several Windows features and all of its performance-sensitive paths behave better with the true flag set. Then size honestly: 4 vCPUs and 8 GB RAM is a realistic floor for a Windows 11 guest you intend to click around in, and remember the host must still feed ESXi and Proxmox themselves. Starving the nest to feed the guest just moves the slowness up a layer.
Windows 11 wants a TPM 2.0, and Proxmox can provide one as an emulated TPM device attached to the VM — no physical chip is involved, which is why it works even nested: the requirement is satisfied by Proxmox's emulation, not by anything passed through from ESXi. Add the TPM state device when creating the VM, use UEFI (OVMF) firmware as Windows 11 expects, and the installer proceeds normally. The tax still applies to everything after the install, but the install itself is fully legitimate.
Nested Windows earns its place for install testing, update rehearsal, GPO and software trials, driver experiments and training — procedural work where correctness matters and speed is secondary. It does not earn a place as anyone's daily desktop, a build machine, or anything with a deadline. That is not a failure of the setup; it is the setup's actual specification. Keep a nested Windows around as a test bench and it will save you from experimenting on real machines — the most valuable service a lab provides.
Watch the video to build the nested platform first — a Windows test bench is the second thing to create in it, right after a container.
▶️ Watch Full VideoNo — this is the expected behaviour with a VirtIO disk before its driver is loaded. Windows setup has no built-in driver for VirtIO storage, so the disk is invisible until you click Load driver and point setup at the virtio-win ISO you attached as a second CD drive. Choose the folder matching your Windows version, and the disk appears immediately.
Yes. Nesting changes the plumbing, not the licensing: a Windows guest inside Proxmox inside ESXi is still a Windows installation and is licensed like any other virtual machine under the terms that apply to you. The lab being nested, free or temporary does not create an exception — plan licences for guests exactly as you would on bare metal.
You can remove its handicaps — VirtIO drivers, host CPU type, sensible sizing, SSD-backed storage — and those steps are worth real, noticeable speed. But the structural double translation remains no matter how generous the resources are. Expect a usable test bench, not a snappy workstation, and you will be pleased rather than disappointed.