When using LoadRunner VuGen TrueClient for browser-based performance testing, understanding event-based timing is critical. In a VIN Search transaction, a mismatch was observed between tool metrics and actual user experience after backend optimization.

Problem Observed

Before Optimization:

  • Actual VIN Search time: ~9 seconds
  • VuGen TrueClient reported: ~9 seconds
  • No discrepancy

After Optimization:

  • Actual VIN Search time: 2–3 seconds
  • VuGen TrueClient reported: ~9 seconds
  • Apparent regression in reports despite real improvement

Why This Happened

TrueClient does not inherently know when a business transaction is complete. It relies on configured start and end events.

By default, the protocol uses “Network Completed” as the end trigger, which includes:

  • VIN search request
  • Server processing
  • HTML rendering
  • JavaScript execution
  • CSS, images, fonts, and other resource loading
  • Post-load background network calls

For highly dynamic web applications, this can significantly inflate reported response times.

What Was Changed

Start Event:

  • Triggered just before pressing ENTER after VIN entry

End Event:

  • Set to “Action Completed” when VIN details were visible on screen

Excluded:

  • All non-critical post-render background activity from timing

Outcome

  • VuGen reported response times aligned with manual stopwatch measurements (2–3 seconds)
  • Stakeholders regained confidence in performance metrics
  • Test results accurately reflected real user experience

Technical Takeaway

Always customize TrueClient start and end events to match business KPIs instead of relying on default network timing triggers.