On October 22 Google described Agent Compute Engine: every AI agent session gets its own microVM, which is checkpointed while the model thinks, cloned copy-on-write from warm snapshots, and given no network card. You can’t use it yet, and the post has no latency or density numbers. So I built the same pattern on Firecracker in about 2,200 lines of Go and measured it on two machines. Sixty-four idle forks of a 512 MiB VM cost about 3 MiB of host memory each. On bare metal, a snapshot restore answers in 25 ms, 26 times faster than a cold boot, and 64 forks started at once are all ready in about 150 ms. On a Mac mini under nested virtualization, twelve forks started at once never became ready at all, and that failure taught me the most.