Cloudflare rebuilds Containers for agent sandboxes, with 6x faster starts
Cloudflare rebuilt Containers for agent workloads on September 30, 2026. Agents can now choose the sandbox image and instance type at runtime, and the median cold start dropped from 4.05 seconds to 648 milliseconds in ComputeSDK's benchmark. Filesystem snapshots for saving and restoring a workspace are in public beta, and Durable Objects now control containers directly through ctx.container. The old Container and Sandbox classes are supported until December 31, 2026.
Why it matters
A sub-second start means an agent can open a fresh sandbox per task instead of reusing a warm one, which is cleaner and safer. Snapshots remove the setup time from every run after the first.
Who should care
Teams running generated or untrusted code for agents
What you can do
Plan the move to the Durable Object API before the legacy classes stop being supported at the end of the year.