Blacksmith vs Depot: CPU Speed vs Docker Build Caching

By Daniel Zoghalchali·Latchkey

Blacksmith and Depot both beat GitHub-hosted runners, but they optimize opposite bottlenecks. Your pipeline decides the winner.

Blacksmith is known for high-clock-speed CPU runners; Depot is known for accelerating Docker image builds with a remote build cache. Choosing between them is really about diagnosing your own bottleneck. This is the honest split, plus where a self-healing option comes in. Verify current pricing and specs on each vendor site.

Blacksmith vs Depot at a glance

	Blacksmith	Depot
Known for	High-clock-speed CPU runners	Docker build acceleration + remote cache
Best workload	Single-threaded build and test	Container-image-heavy pipelines
Speeds up	CPU-bound steps	Repeated Docker builds via cache
Self-healing flaky jobs	No	No

Pick Blacksmith if

Your build and test time is CPU-bound and faster per-core hardware is the clearest win. High-frequency CPUs help single-threaded compilation and test suites that do not parallelize well.

Pick Depot if

Your CI is dominated by building container images and remote build caching is the bottleneck. Depot is known for making repeated Docker builds much faster by reusing cached layers across runs.

If the real problem is cost and flakiness

Neither is designed to recover from flaky, transient failures, and both compete mainly on speed. If your pain is a high bill plus re-running red builds, Latchkey adds self-healing on managed runners priced roughly 70% below GitHub-hosted. It is worth benchmarking alongside them rather than instead of the one that matches your bottleneck.

The verdict

CPU-bound work: Blacksmith. Docker-build-bound work: Depot. If cost and flaky re-runs are the deeper issue, evaluate Latchkey self-healing alongside your speed pick. Diagnose your bottleneck first, then verify current pricing.

Switching costs you one line

Latchkey runners are a drop-in replacement: change runs-on: and the rest of the workflow is untouched. Self-healing is on by default, so transient failures are fixed and retried instead of failing the build.

.github/workflows/ci.yml

# before
    runs-on: ubuntu-latest

# after
    runs-on: latchkey-medium

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Frequently asked questions

Is Blacksmith or Depot faster?

It depends on the bottleneck. Blacksmith is known for faster single-threaded CPU work; Depot is known for faster repeated Docker builds via remote caching. They are fastest at different things, so match to your pipeline.

References

GitHub Actions documentation