# AI Coding Made CI a Bottleneck > Linear reworked CI to cut PR wait time from 6+ minutes to 5 minutes. - Title: AI Coding Made CI a Bottleneck · Linear | Shortify - Summary: Linear reworked CI to cut PR wait time from 6+ minutes to 5 minutes. Linear reduced CI wait time from over 6 minutes to just over 5 minutes by optimizing… - Keywords: linear, test suite, typescript, github actions, pnpm, vitest, api test, shard, technology, startups, Coding, Made - Source: Linear — https://linear.app/now/ci-bottleneck-reworked - Published: 2026-09-21T12:26:00+00:00 - Read time: 2 min - Topics: linear, ci, pr, test suite, typescript, github actions, pnpm, vitest, api test, shard, technology, startups ## AI coding made CI a bottleneck AI coding has made CI a bottleneck, so we reworked ours to keep up. > AI coding has made CI a bottleneck, so we reworked ours to keep up ## PR wait time dropped from 6+ minutes PR wait time dropped from more than 6 minutes to just over 5 minutes. > PR wait time dropped from more than 6 minutes to just over 5 minutes ## Runner time cut in half Runner time per test cut roughly in half. > runner time per test cut roughly in half ## Test suite performance improved Test suite performance indexed to first week of January with white line tracking machine time per test. > Test suite performance indexed to first week of January with white line tracking machine time per test ## Four key CI improvements Upgraded infrastructure and tooling, optimized jobs that gate other work, reduced repeated setup, made test execution more efficient. > Upgraded infrastructure and tooling, optimized jobs that gate other work, reduced repeated setup, made test execution more efficient ## Upgraded infrastructure and tooling Moving workloads off GitHub Actions to third-party runners with faster CPUs and storage cut jobs by 34% on average. > Moving workloads off GitHub Actions to third-party runners with faster CPUs and storage cut jobs by 34% on average ## Switched to tsgo Switching to tsgo, the native TypeScript compiler, cut weekly median tsc check by 73%. > Switching to tsgo, the native TypeScript compiler, cut weekly median tsc check by 73% ## Lint without type checker Rewrote lint rules to use static analysis over abstract syntax tree, reducing API lint time by 68%. > Rewrote lint rules to use static analysis over abstract syntax tree, reducing API lint time by 68% ## Optimized jobs that gate other work Small jobs that gate other work were critical path items, causing disproportionate delays. > Small jobs that gate other work were critical path items, causing disproportionate delays ## Fetch only what each job needs Capped fetch depth to reduce change-detection job time from 94 seconds to 20 seconds. > Capped fetch depth to reduce change-detection job time from 94 seconds to 20 seconds ## Make checkout more resilient Replaced actions/checkout with composite action to retry with backoff and use checkout cache. > Replaced actions/checkout with composite action to retry with backoff and use checkout cache ## Minimize critical path Moved cache marker write to job after test shards finish, shaving 42 seconds from merge path. > Moved cache marker write to job after test shards finish, shaving 42 seconds from merge path ## Reduce repeated setup Preinstalled shared dependencies in CI image to cut API test shard setup time by 44%. > Preinstalled shared dependencies in CI image to cut API test shard setup time by 44% ## Make test execution more efficient Split large test files into smaller focused files to improve shard performance by 19%. > Split large test files into smaller focused files to improve shard performance by 19% ## Share module state with isolation Introduced vitest project with isolate: false to share module state, cutting shard time from 300-379 seconds to 195 seconds. > Introduced vitest project with isolate: false to share module state, cutting shard time from 300-379 seconds to 195 seconds ## Key takeaway Linear reduced CI wait time from over 6 minutes to just over 5 minutes by optimizing test execution and infrastructure.