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There is no single fastest setup. Start with the defaults, measure your workload, and change one setting at a time. Run these commands before tuning anything:
msb doctor checks host capabilities. msb inspect shows the settings that a sandbox actually uses.

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Quick guide

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Storage layout: layered or flat

The default layered root shares OCI layers between sandboxes. A flat root turns the image into one ext4 disk and clones it for each sandbox. This can improve creation time and filesystem-heavy workloads on hosts with copy-on-write cloning.
clone=auto uses a native copy-on-write clone when available and falls back to a sparse copy. Use the layered root when image layer sharing or maximum portability matters more. See OCI images for image behavior and Bootstrap for flat root details.

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CPU placement

CPU placement controls where vCPU threads run on Linux and Windows. These policies coordinate sandboxes that share the same MSB_HOME. They do not reserve physical cores or isolate other host processes. See CPU placement for setup and limits.

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Transparent huge pages

Transparent huge pages, or THP, control how the guest handles large memory mappings. THP changes take effect the next time the sandbox boots. Keep madvise unless real workload tests show a clear improvement.

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Buffered block writeback

On Linux, block writeback limits how much buffered disk data active sandboxes can hold in host memory.
  • auto chooses safe limits from the host. This is the recommended setting.
  • fixed uses limits that you provide.
  • off disables the limits for new sandboxes.
This setting has no effect on non-Linux hosts, read-only disks, or direct I/O. See Global config for the available fields.

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Host interrupt acceleration

On Linux x86 hosts, AMD AVIC and Intel APICv can make virtual interrupt delivery faster. These are host KVM settings, not sandbox settings. Check their status with msb doctor. Read Linux troubleshooting before changing a KVM module because the change affects every VM on the host.

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Optimizations that are not knobs

Microsandbox automatically selects compatible filesystem, guest kernel, interrupt, and vCPU affinity optimizations. These implementation details do not have user-facing settings.

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Measure the result

Keep the image, CPU and memory limits, storage, host power settings, and concurrency unchanged while comparing settings. Measure sandbox creation separately from workload performance.