Doc: Note on the BuildKit / QEMU performance

README.md

@@ -195,7 +195,7 @@ These methods can be used to build a container image, at the time of writing:
 | [img](https://github.com/genuinetools/img#running-with-kubernetes), [BuildKit](https://github.com/moby/buildkit) | 🟩🟩🟩 | 🟩🟩🟥 | 🟩🟥🟥 | Local CLI | CLI to build the images. Can build different architectures on a single machine. Requires [Seccomp](https://en.wikipedia.org/wiki/Seccomp) disabled and [AppArmor](https://apparmor.net) disabled. |
 | Docker in docker | 🟩🟩🟩 | 🟥🟥🟥 | 🟩🟩🟩 | Local CLI | Before Kubernetes 1.20, it was possible to build container images in the agent, using the Docker socket. This is not possible anymore, as Kubernetes [deprecated the Docker socket](https://kubernetes.io/blog/2020/12/02/dont-panic-kubernetes-and-docker) in favor of the [Container Runtime Interface](https://kubernetes.io/blog/2016/12/container-runtime-interface-cri-in-kubernetes). |
 
-We choose [BuildKit](https://github.com/moby/buildkit) for this project. [Its licence](https://raw.githubusercontent.com/moby/buildkit/v0.11.5/LICENSE) allows commercial use, and the project and mainly maintained, as the time of writing, by Docker, Netlix and Microsoft.
+We choose BuildKit for this project. [Its licence](https://raw.githubusercontent.com/moby/buildkit/v0.11.5/LICENSE) allows commercial use, and the project and mainly maintained, as the time of writing, by Docker, Netlix and Microsoft.
 
 #### How to use the bundled BuildKit
 
@@ -228,6 +228,10 @@ steps:
 
 Out of the box, argument `--opt platform=linux/amd64,linux/arm64` can be added to build an image compatible with multiple architectures ([more can be specified](https://github.com/moby/buildkit/blob/v0.11.5/docs/multi-platform.md)). Multiple cache strategies [are available](https://github.com/moby/buildkit/tree/v0.11.5#cache) (including container registry, Azure Storage Blob, AWS S3).
 
+#### BuildKit and the performance
+
+BuildKit works by virtualization in the user space. You can't expect build times as short as native (on your laptop for example). [QEMU](https://www.qemu.org) is used as a backend. This has the advantage of being able to create images for different architectures than your processor. Virtualization-wise, not all CPU models are equivalent, you can [refer to the official project documentation](https://www.qemu.org/docs/master/system/qemu-cpu-models.html) to select the most appropriated CPU model for your Kubernetes Node Pool.
+
 ### Helm values
 
 | Parameter | Description | Default |