Koyeb has introduced a significant enhancement to its serverless platform by reducing cold start times to around 200ms for CPU workloads using a feature called Light Sleep. This was achieved by transitioning from Firecracker to Cloud Hypervisor for better hardware support, implementing Kata Containers for flexibility, and leveraging eBPF for efficient idle detection. The company faced challenges with snapshotting, notably with virtio-fs and network restoration, which were overcome by modifying Cloud Hypervisor processes and integrating a scaletozero-agent. This agent, combined with eBPF, allows for precise idle detection and efficient sleep and wake mechanisms for applications, ensuring seamless scaling to zero without disrupting services. The new setup, now available in public preview, aims to extend similar capabilities to GPU-based services, addressing the complexities of VRAM preservation.