Review Latency
Review Latency measures the time between when a pull request is opened and when the first meaningful review begins. It reflects how responsive a team is to new code submissions and how quickly feedback loops start.
Calculation
Review Latency is typically defined as the time between pull request creation and the first non-trivial reviewer comment or approval. This excludes automated checks and self-comments by the author.
This metric is calculated by measuring the time elapsed from PR creation to first reviewer response:
review latency = first review timestamp – pull request creation timestamp
Goals
Review Latency helps teams improve delivery flow and reduce delays in the coding process. It answers questions like:
- How long does work sit idle before feedback begins?
- Are reviewers responding quickly and consistently?
- Are we enabling faster iteration and earlier problem detection?
Reducing latency supports tighter delivery loops and better developer experience. For background on review responsiveness, see Microsoft Research’s empirical study on pull request practices.
Variations
Review Latency may also be called Time to First Review, PR Feedback Delay, or Review Response Time. Common segmentations include:
- By team or repo, to highlight review backlogs or bottlenecks
- By PR size, since large PRs often receive slower responses
- By day of week or time of day, to uncover staffing or process gaps
Some teams track this metric per reviewer or contributor to encourage accountability. Others include secondary review rounds to measure total feedback coverage, but the most common definition focuses on time to first response.
Limitations
Review Latency shows how long it takes to begin feedback, not how long it takes to complete it. A fast response followed by stalled approval still impacts delivery.
The metric also doesn’t account for context, some work may intentionally wait for higher-priority reviews. Used alone, latency may create pressure to respond quickly without providing thoughtful feedback.
To understand how review timing impacts delivery, use this metric with:
| Complementary Metric | Why It’s Relevant |
|---|---|
| Cycle Time | Highlights how review delays impact overall time to complete work. |
| Pull Request Frequency | Helps detect whether high submission volume is contributing to latency. |
| Pull Request Size | Reveals whether large or complex PRs are causing review hesitation. |
Optimization
Reducing Review Latency improves team responsiveness and speeds up feedback loops without sacrificing quality.
-
Set expectations for reviewers. Use shared Code Review Best Practices and SLAs to encourage timely feedback, especially on small and urgent changes.
-
Auto-assign reviewers. Configure bots or rules to assign the right reviewers immediately when PRs are opened, reducing manual coordination time.
-
Balance workload across reviewers. Avoid review bottlenecks by monitoring load per person and adjusting contributor responsibilities or team norms.
-
Encourage smaller PRs. Long or complex changes often sit in queues. Apply Trunk-Based Development and iterative task breakdown to keep PRs reviewable.
-
Track and surface latency. Visualize review delay in dashboards or standups so teams can address review drag before it slows delivery.
Improving Review Latency leads to faster iteration, better collaboration, and fewer blockers, giving developers the feedback they need when it matters most.
