Consistent testing methodology ensures performance measurements are comparable across time and between Editions. This page documents the tools, procedures, and metrics used for Velocity Stack performance testing.
Testing Tools
| Tool | Purpose | Key Strengths |
|---|---|---|
| Pingdom | Overall performance grade | Simple scoring, waterfall analysis, historical tracking |
| GTmetrix | Detailed Core Web Vitals | Lighthouse integration, video playback, comparison |
| PageSpeed Insights | Google’s official metrics | Real user data (CrUX), mobile/desktop split |
| Chrome DevTools | Request-level debugging | Network throttling, cache control, waterfall |
Primary vs. Secondary Tools
Primary: Pingdom
Pingdom is the primary tool for Velocity Stack baseline testing because:
- Consistent test infrastructure across runs
- Clear single-number performance grade
- Detailed waterfall for debugging
- Content breakdown by type and domain
- Historical tracking for trend analysis
Secondary: GTmetrix & PageSpeed Insights
Used for deeper analysis when Pingdom identifies issues:
- Core Web Vitals breakdown (LCP, FID, CLS)
- Specific optimization recommendations
- Mobile vs. desktop comparison
- Real user experience data (PageSpeed only)
Test Procedure
Step 1: Pre-Test Preparation
- Verify site is accessible (no maintenance mode)
- Confirm cache is enabled and warmed
- Check CDN Layer status is active
- Note any recent changes since last test
Step 2: Cache Warming
- Visit the test URL in a browser
- Open DevTools → Network tab
- Check response headers for cache hit indicator
- If “miss”, refresh and verify “hit” on second request
Step 3: Run Pingdom Test
- Navigate to tools.pingdom.com
- Enter the test URL
- Select test location (use consistent location)
- Click “Start Test”
- Wait for results
Step 4: Record Results
Capture the following metrics:
- Performance grade (letter and number)
- Page size (KB)
- Load time (ms)
- Request count
- Content breakdown by type
- Any failed requests or errors
Step 5: Screenshot & Archive
- Screenshot the summary panel
- Screenshot the waterfall (if notable)
- Screenshot content breakdown
- Save with naming convention:
[tool]-[date]-[metric].webp
Test Location Selection
Choose a test location based on target audience:
| Audience | Recommended Location | Notes |
|---|---|---|
| US East Coast | New York, Washington DC | Good for US-focused sites |
| US West Coast | San Francisco, Los Angeles | Tests cross-country latency |
| Europe | London, Frankfurt | Tests CDN edge performance |
| Global | Multiple locations | Run from 3+ locations for comparison |
Important: Use the same test location for all baseline comparisons. Changing locations invalidates trend data.
Metrics Definitions
Core Web Vitals
| Metric | What It Measures | Good | Poor |
|---|---|---|---|
| Largest Contentful Paint (LCP) | Loading — when main content is visible | ≤ 2.5s | > 4.0s |
| First Input Delay (FID) | Interactivity — response to first interaction | ≤ 100ms | > 300ms |
| Cumulative Layout Shift (CLS) | Visual stability — unexpected layout movement | ≤ 0.1 | > 0.25 |
Supporting Metrics
| Metric | What It Measures | Target |
|---|---|---|
| Time to First Byte (TTFB) | Server response time | < 600ms |
| First Contentful Paint (FCP) | First visible content rendered | < 1.8s |
| Total Blocking Time (TBT) | Main thread blocked by JS | < 200ms |
| Speed Index | How quickly content is visually displayed | < 3.4s |
| Time to Interactive (TTI) | Page fully interactive | < 3.8s |
Testing Frequency
| Event | Test Required | Tools |
|---|---|---|
| New Edition deployed | Full baseline | Pingdom, GTmetrix, PageSpeed |
| Template version update | Comparison test | Pingdom |
| Capability update | Spot check | Pingdom |
| Cache configuration change | Before/after comparison | Pingdom, DevTools |
| Monthly maintenance | Trend tracking | Pingdom |
| Performance issue reported | Diagnostic | All tools |
Results Documentation
File Naming Convention
[tool]-[YYYY-MM-DD]-[HH_MM_SS]-[metric].webp
Examples:
pingdom-2026-01-11-01_28_06-performance.webp
pingdom-2026-01-11-01_28_06-file-requests.webp
pingdom-2026-01-11-01_28_06-grouped-content-type.png
gtmetrix-2026-01-15-performance-report.webpStorage Location
- Documentation Platform: /Performance-Test-Results/[Edition]/[Date]/
- This site: Media library with descriptive alt text
Interpreting Results
Green Flags
- Performance grade A (90+)
- All requests from single domain
- Page size under 100 KB
- Load time under 200ms (cached)
- Zero layout shift (CLS = 0)
- Cache hit on repeat requests
Red Flags
Render-blocking resources
Third-party domain requests
Failed requests (4xx, 5xx errors)
Page size over 1 MB
Load time over 3 seconds
High CLS (content jumping)
Cache miss on repeat requests