AI coding has made CI a bottleneck, so we reworked ours to keep up
Despite our test suites almost quadrupling since the start of the year, we brought pull request wait time down from more than 6 minutes to just over 5, while cutting runner time per test roughly in half.This is test suite performance indexed to the first week of January. Moving our workloads off GitHub Actions to third-party runners with faster CPUs, higher-performance storage, and better cache infrastructure gave us faster machines to run the same pipeline on. In a like-for-like comparison of the two days either side of the switch, jobs ran 34% faster on average, with some workloads like tsc dropping 52%.Separately, modernizing our toolchain also paid off.
- ▪Despite our test suites almost quadrupling since the start of the year, we brought pull request wait time down from more than 6 minutes to just over 5, while cutting runner time per test roughly in half.This is test suite performance indexe
- ▪Moving our workloads off GitHub Actions to third-party runners with faster CPUs, higher-performance storage, and better cache infrastructure gave us faster machines to run the same pipeline on.
- ▪In a like-for-like comparison of the two days either side of the switch, jobs ran 34% faster on average, with some workloads like tsc dropping 52%.Separately, modernizing our toolchain also paid off.
Hacker News (AI / LLM) files mainly under ai. We currently carry 5,882 of its stories.
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Record
| Original publisher | Linear |
| Canonical URL | https://linear.app/now/ci-bottleneck-reworked |
| Publication time | Mon, 21 Sep 2026 19:23:33 +0000 |
| Retrieval time | 2026-09-21T19:33:49.174Z |
| Last seen | 2026-09-21T19:33:49.174Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | RV1JzI86XsH1 · 1 stories |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
Rights status (four layers)
WeSearch handling by dimension
| Indexing | May the item be indexed (stored, ranked, made findable)? | Allowed |
| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
NowFrom the teamAI coding has made CI a bottleneck, so we reworked ours to keep upMufeez Amjad·September 21, 2026Earlier this year, I opened Linear to find that Tuomas, our CTO, had assigned an issue to me, titled “CI costs are high.” While I was at it, he also wanted me to make CI faster.Agents have made it exponentially faster to ship code, but validating those changes hasn’t quite kept up at the same rate. Every PR still has to pass through CI, so as development accelerates, CI becomes a bottleneck, driving up infrastructure costs and leaving developers and agents waiting longer for feedback.In our pursuit to make CI more performant at Linear, we optimized for how long a PR waits on CI and how much runner time it consumes.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Linear.
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