The hosts a managed sandbox runs on, what its CPU looks like from inside, and how fast it is.
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Hosts
Every sandbox is a Firecracker virtual machine on a physical server the platform runs. Today those are AMD servers: AMD Ryzen 9 9950X hosts and AMD EPYC hosts. You cannot choose the host; the placement shows on the sandbox (engine_id).
- vCPUs are shared. A sandbox's vCPUs are threads on the host, not cores set aside for it. Sandboxes on the same host share CPU time, so a busy host can make a run slower.
- Memory is the sandbox's own. The memory you ask for is reserved for the box while it runs.
- No GPU. Sandboxes have none.
The CPU from inside
The guest sees its vCPUs as one socket with one thread per core. /proc/cpuinfo names a generic AMD EPYC model, whatever the host is.
The guest gets every compute instruction the host has: on a 9950X host that includes AVX-512, VAES, VPCLMULQDQ and SHA. It does not see host-only features (power and frequency controls, performance counters, nested virtualization).
Performance
The V8 Web Tooling Benchmark, the Node.js workload of the Phoronix Test Suite (pts/node-web-tooling-1.0.1), in one sandbox on a quiet AMD Ryzen 9 9950X host:
| Machine | Runs per second |
|---|---|
| Sandbox, 4 vCPUs, 8 GiB | 27.2–27.75 |
| The same host without a VM, all 32 threads | 30.2 |
Measured 2026-11-09: Node.js 22.23.1, Web Tooling Benchmark 0.5.3, 3 to 5 passes, median of each run's geometric mean. Higher is better.
A sandbox runs at about 90% of the bare host. On a host where many sandboxes are busy at once, each one is slower; the figure above is a quiet host.