Tests quadrupled, yet Linear cut CI wait to five minutes
AI coding made CI the new bottleneck; Linear's self-measured numbers and fixes are directly useful to engineering teams, but all first-party.
Original event 2026-09-21
Linear says its test suites nearly quadrupled this year, yet pull request CI wait fell from over 6 minutes to just over 5, with runner time per test roughly halved.
The work had two layers: moving to third-party runners with faster CPUs and better caching made like-for-like jobs 34% faster on average, and switching to the native TypeScript compiler cut median typecheck time by 73%. The other layer saves machine time: linting without type information, trimming small jobs off the critical path, and cutting per-shard setup by roughly 44%.
All figures are Linear's own measurements with no third-party verification, and the findings come from one TypeScript monorepo. Still, the claim that AI coding has made CI the bottleneck, plus the concrete optimization list, is directly useful to engineering teams facing the same surge in agent-submitted code.