fix: use monotonic clock for measuring spans

[kishore03109]

Context

Good pre-read

Tracking of spans might be inaccurate as a time-of-day clock is subject to moving forward or backward due to NTP stepping and is subject to leap second adjustments. Using a monotonic clock allows us to have a more accurate measurement of elapsed time on a single node.

Did a similar fix for ASG

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
starter-kit	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 27, 2025 9:36am

[kishore03109]

• fix: use monotonic clock for measuring spans #475 👈 (View in Graphite)
• main

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[datadog-opengovsg]

Datadog Report

Branch report: fix_use_monotonic_clock_for_measuring_spans
Commit report: 3083fe3
Test service: starter-kit

✅ 0 Failed, 12 Passed, 0 Skipped, 11.9s Total Time

[Copilot]

Pull Request Overview

This PR improves the accuracy of span measurements by switching from a time-of-day clock (Date.now()) to a monotonic clock (performance.now()).

• Replaces Date.now() with performance.now() for better accuracy
• Rounds the elapsed time for logging consistency

Comments suppressed due to low confidence (2)

src/server/trpc.ts:48

• Ensure that the global 'performance' object is available in your server environment or is properly polyfilled, as some Node.js versions may not support it.

  const start = performance.now()

src/server/trpc.ts:55

• [nitpick] Verify whether rounding the elapsed time to an integer is required for your use-case or if preserving fractional milliseconds would provide more precision.

  const durationInMs = Math.round(performance.now() - start)

[karrui]

Lgtm. Can add into knowledge base?