Async Code Reviews Are Choking Your Company’s Throughput
summary
Analysis of 40,000+ PRs shows async, small-PR workflows increase per-line review wait time exponentially and cut flow efficiency, while very large PRs erode review engagement and quality; engagement is measured as non-trivial comments (>4 words), size by lines changed, and wait time normalized per LOC. A highlighted case reports a 500-PR sample where a 6-month merge window accumulates ~28 months of reviewer wait time; a team using trunk-based mob practices records 107 commits in 9h20m with ~2.3 minute mean integration, demonstrating near-zero review latency and preserved throughput plus quality.
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chapters (18)
- 0:00The case for async reviews
- 2:25Async means delays
- 4:22Study context and metrics
- 6:26Engagement and PR size
- 9:26Feedback quality issues
- 12:28Waiting time analysis
- 16:07Waiting time by size
- 18:58Economics of code review
- 22:16Merge begging and nitpicks
- 25:14System dynamics modeling
- 29:15Flow efficiency plummeted
- 31:46WIP and inventory effects
- 35:13Finding the sweet spot
- 37:28Moving to continuous review
- 40:05Pair and mob programming
- 42:29PR score formula
- 44:28Results and trunk-based
- 47:04Q&A and conclusion
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