CI runner benchmarks and guides for GitHub Actions, CircleCI and Semaphore

Vitest sharding: how to split your suite across CI machines without lying to yourself

Vitest sharding can cut a 20-minute suite to 6. It can also hide flaky tests, quadruple your setup cost, and shred your reporting. Here is how to do it right.

Vitest slow? Read the duration breakdown before you touch your config

Vitest tells you exactly where the time goes. Most teams never read it. Here's how to diagnose a slow Vitest suite and fix the real bottleneck instead of guessing.

Vitest performance: why your suite is fast locally and slow in CI

Vitest is fast on your laptop and mysteriously slow in CI. Here's where the time actually goes, and the config changes that fix it without wrecking reliability.

Docker layer caching on GitHub Actions runners: benchmarks of what actually works

We benchmarked four Docker layer caching strategies on GitHub Actions. The winner cut a 8-minute build to 48 seconds. The most popular option barely helped.

GitHub Actions vs BuildPulse runners, benchmarked

Real open-source workloads, pinned commits, public runs you can fork and rerun: the same jobs finish 1.3 to 2.1x sooner and cost 50 to 68 percent less. Every number links to a run.

How to migrate from GitHub-hosted runners to BuildPulse runners

Your workflows stay in GitHub Actions: same YAML, same secrets, same PR checks. The only thing that changes is which machine picks up the job. The whole migration, from our own thirteen-repo run of it.

We moved 13 CI repos to our own runners in one afternoon. Here is everything that broke.

We migrated all thirteen of our public example repos from GitHub-hosted runners to BuildPulse runners. 13 of 13 ended green, and most of what broke was already broken. The honest ledger, with every run linked.

Self-hosted GitHub Actions runners vs GitHub-hosted: where queue time actually goes

Queue time is the tax nobody itemizes. We break down where GitHub Actions runner queue time actually goes — with numbers — and why warm per-tenant pools win.

Vitest isolate: when turning it off speeds up CI and when it breaks your tests

Disabling Vitest isolate can cut your test suite time in half — or surface a dozen flaky tests you never knew you had. Here's the tradeoff, spelled out.

Jest JUnit output: how to make Jest results readable in CI

Jest prints beautiful output in your terminal and useless output in CI. Here's how to emit JUnit XML that your pipeline can actually parse — and what to watch for.

Stop paying for cold caches: GitHub Actions runner cache benchmarks

The cache/save step looks free in your logs. It isn't. Real numbers on GitHub Actions cache restore times, layer reuse, and when self-hosted runners cut them to zero.

The Vitest cache, explained: what it stores, when to keep it, and when it lies to you

Vitest has two caches, and most teams cache the wrong one in CI. Here's what each does, how to configure them, and how one of them can make your test order nondeterministic.

Vitest performance: why your test suite is slow and how to fix it

Vitest is fast by default, but default isn't always fast enough. Here's how to actually diagnose and fix a slow Vitest suite.

docker/setup-buildx-action@v3: what it does, why it matters, and how to use it right

docker/setup-buildx-action@v3 is two lines of YAML that unlock multi-platform builds, layer caching, and faster CI — if you configure it correctly.

How to Speed Up pytest

pytest running slow? Profile with --durations, parallelize with pytest-xdist worksteal, reuse your Django DB, and shard by duration in CI. 13 proven fixes.

How to Speed Up Vitest

Vitest running slow? 12 practical ways to speed up Vitest locally and in CI: pool tuning, isolate false, changed-only runs, sharding, and cache fixes.

How to Speed Up Playwright Tests

Playwright tests slow in CI? Parallelize with workers and sharding, reuse auth state, cut waits and tracing overhead. A practical 4-pillar speed guide.

Non-obvious ways self-hosting GitHub Actions can increase CI cost.

Runners: With great power comes with great responsibility — it's not all sunshine and rainbows, there are some unobvious challenges.

BuildPulse Runners: Run your GitHub Actions 2x faster, at half the cost.

Runners: Run GitHub Actions builds on our optimized-infrastructure, geared to cut build times and cost.