Vercel cuts Sandbox snapshot creation time by up to 10x to under 0.4 seconds

Snapshot creation drops from 4.4 seconds to under 0.4

Vercel has announced that Sandbox, its isolated compute environment, now creates snapshots up to ten times faster than before. According to a post on the Vercel blog, the median time to create a snapshot has fallen from 4.4 seconds to under 0.4 seconds. Restores have gotten quicker as well: Vercel reports a 50% improvement at the median, from 500 milliseconds down to 250 milliseconds.

What changed in the snapshot format

The speedup comes from changes to the Vercel Hive Snapshot (VHS) format, the mechanism Vercel uses to write and restore sandbox state. According to the blog post, snapshots can now write and restore by reusing frames that already exist in the format, rather than rewriting data that has not changed.

Vercel also redesigned how VHS indexes data. The company says the new indexing scheme lets more read and write operations run in parallel. On the restore side, more of a sandbox's base image can now be rebuilt at the same time as user data, instead of the two being handled one after the other. Together, these changes compress the time spent on both ends of the snapshot lifecycle.

Persistent sandboxes and rollout

Persistent sandboxes, which Vercel notes are the default mode, automatically take a snapshot whenever a session stops and resume from the latest snapshot afterwards. Faster snapshot creation therefore directly shortens the pause a developer or an automated workflow experiences when ending and restarting a session.

The change requires no configuration. All new snapshots use the improved format and pick up the speedups automatically. Snapshots that already exist keep the previous format, and the announcement does not describe a migration path for them.

Why it matters

Sandboxes are typically used as short-lived environments for running builds, installing dependencies, executing tests or reproducing issues, and they are increasingly invoked by automated agents rather than humans. In those workflows, snapshot creation often sits on the critical path: every time a session ends, its state has to be persisted before the environment can be released. A four-plus-second pause per snapshot accumulates quickly when a pipeline cycles through dozens of environments.

Cutting the median to under 0.4 seconds, and restores to 250 milliseconds, makes that pause close to negligible, which lowers the practical cost of tearing down and restoring state frequently. For teams already running workloads in Vercel Sandbox, the improvement arrives with no code changes, since new snapshots adopt the new format on their own.

The upgrade is also a signal of where Vercel is investing. Faster snapshot and restore times make ephemeral, stateful compute cheaper to rely on, a model that fits agentic development tooling, where environments are created and discarded at high frequency. Improving the underlying storage format rather than asking developers to change how they use sandboxes suggests Vercel expects this workload pattern to keep growing.