How We Boot Firecracker VMs in Under 125ms on Apple Silicon
[Engineering]

How We Boot Firecracker VMs in Under 125ms on Apple Silicon

2026-03-05

Kai Nakamura

Kai Nakamura

Engineering

Elias Brandt

Elias Brandt

Engineering

Overview

A deep dive into the architectural decisions that let ArcBox Desktop spin up a fully isolated microVM faster than most containers start.

The Challenge

Booting virtual machines has traditionally been a slow process, taking seconds or even minutes on most platforms. We set out to prove that on Apple Silicon, we could achieve sub-125ms startup times.

Our Approach

The key to our success was a combination of:

  1. Lightweight Firecracker VMs - Firecracker provides a minimal hypervisor overhead
  2. Apple Silicon Optimization - Native instruction support and memory efficiency
  3. Pre-warming Strategies - Clever caching and preparation techniques

Results

Through careful optimization and architectural decisions, we achieved consistent sub-125ms boot times for fully isolated microVMs, beating traditional containers on startup performance.

Future Work

We're continuing to push these boundaries and exploring even faster startup times while maintaining security and isolation guarantees.

That's all. Except not.

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