Site speed performance analysis helps you understand how quickly your pages load and identify performance bottlenecks that hurt user experience and conversions. Slow pages drive away visitors and impact search rankings. This analysis reveals which pages need optimization and how speed affects engagement.
Before you start
You need:
- A connected Google Analytics 4 property in Settings → Connections
- At least 14 days of traffic data for reliable speed metrics
- Starter plan or higher (8 credits per analysis)
- Enhanced measurement enabled in GA4 (for full speed data)
If you haven't connected Google Analytics 4 yet, follow the connection guide.
What you can analyze
Site speed analysis provides comprehensive performance insights:
Core Web Vitals:- Largest Contentful Paint (LCP) - Loading performance
- First Input Delay (FID) - Interactivity
- Cumulative Layout Shift (CLS) - Visual stability
- Average page load time by page
- Server response times
- Document interactive time
- DOM content loaded timing
- Speed by device type (mobile, desktop, tablet)
- Geographic performance (countries, regions)
- Speed by connection type
- Browser-specific performance
- Slowest loading pages
- Pages with poor engagement due to speed
- High bounce rate pages with speed issues
- Mobile vs desktop performance gaps
Running speed analysis
To analyze site speed:
- Go to Insights in the main navigation
- Select Google Analytics 4 from the submenu
- Choose Site speed performance
- Select your date range (defaults to last 30 days)
- Optionally filter by URL pattern
- Toggle device or geographic breakdown if needed
- Click Analyze
The analysis typically takes 20-30 seconds and costs 8 credits.
Understanding Core Web Vitals
Google's Core Web Vitals measure user experience:
Largest Contentful Paint (LCP) - How long until the largest content element renders. Measures perceived load speed.- Good: Under 2.5 seconds
- Needs improvement: 2.5-4 seconds
- Poor: Over 4 seconds
- Good: Under 100ms
- Needs improvement: 100-300ms
- Poor: Over 300ms
- Good: Under 0.1
- Needs improvement: 0.1-0.25
- Poor: Over 0.25
These metrics directly impact SEO rankings. Google uses them as ranking factors.
Understanding page load metrics
Average page load time - Total time from navigation start to page fully loaded. Includes all resources (images, scripts, fonts). Server response time - How long your server takes to respond to requests. Slow servers delay everything else. Document interactive time - When users can start interacting with the page. JavaScript-heavy sites may load visually but remain unresponsive. DOM content loaded - When HTML is parsed and DOM is ready. Shows how quickly core content becomes available.Identifying slow pages
The analysis highlights problem pages:
High bounce rate slow pages - Pages where users leave immediately due to slow loading. Top optimization priority since speed directly drives abandonment. Low engagement slow pages - Pages with poor engagement metrics correlated with slow load times. Users who wait still have poor experiences. Mobile slow pages - Pages that load slowly on mobile devices. Mobile users are less patient and more likely to abandon. Critical path slow pages - Important pages (homepage, product pages, checkout) that load slowly. These have disproportionate business impact.Device performance comparison
Speed varies dramatically by device:
Mobile performance:- Typically 2-3x slower than desktop
- Constrained by device power and connection
- Most sensitive to large images and JavaScript
- Highest optimization priority (most traffic comes from mobile)
- Usually best performance
- More powerful processors and faster connections
- Can handle larger resources
- Good baseline for comparison
- Between mobile and desktop
- Consider tablet experiences separately
- Often used for more leisurely browsing
Geographic performance
Speed varies by user location:
Server distance - Users far from servers experience higher latency. Consider CDN for global audience. Connection quality - Developing markets often have slower connections. Optimize aggressively for these markets if they're important. Regional variations - Some countries have infrastructure challenges. Understand your target markets' constraints.Common performance issues
Large images:- Unoptimized images are the most common culprit
- Resize to appropriate dimensions
- Compress without visible quality loss
- Use modern formats (WebP, AVIF)
- Implement lazy loading
- Too much JavaScript delays interactivity
- Remove unused libraries
- Defer non-critical scripts
- Code-split large bundles
- Minimize third-party scripts
- CSS and JavaScript that block rendering
- Inline critical CSS
- Defer non-critical CSS
- Use async/defer for scripts
- Eliminate render-blocking fonts
- Slow server responses delay everything
- Upgrade hosting if needed
- Implement server-side caching
- Use CDN for static assets
- Optimize database queries
- Ads, analytics, social widgets slow pages
- Audit necessity of each script
- Load third-party resources asynchronously
- Consider removing low-value scripts
- Use tag manager to control loading
Optimizing page speed
For poor LCP:- Optimize largest image or video
- Implement lazy loading for below-fold content
- Use CDN for faster asset delivery
- Preload critical resources
- Improve server response time
- Reduce JavaScript execution time
- Break up long tasks
- Use web workers for heavy computation
- Minimize third-party code
- Implement code splitting
- Set size attributes on images and videos
- Reserve space for dynamic content
- Avoid inserting content above existing content
- Use transform animations instead of layout changes
- Preload fonts to prevent font swaps
Monitoring speed over time
Regular analysis:- Run speed analysis monthly
- Track Core Web Vitals trends
- Monitor after major site changes
- Watch for degradation
- Check speed impact of new features
- Verify optimizations improved metrics
- Test across devices and locations
- Ensure changes don't hurt performance
- Set performance budgets
- Monitor in development environments
- Test before deploying to production
- Make speed a team priority
Speed impact on conversions
Research shows performance directly affects business metrics:
Abandonment rates:- 1 second delay = 7% reduction in conversions
- 3 second load time = 32% higher bounce rate
- 5 seconds = 90% of mobile users leave
- 100ms improvement = 1% revenue increase
- Each second improvement significantly boosts conversion rates
- Speed improvements have compounding effects
- Core Web Vitals are ranking factors
- Faster pages rank higher in search
- Better engagement signals improve rankings
- Speed improvements boost organic traffic
Best practices
Mobile-first optimization:- Test on real mobile devices
- Optimize for 3G connections
- Prioritize mobile user experience
- Most users browse on mobile
- Don't just optimize once
- New features often add weight
- Regular audits catch degradation
- Speed is an ongoing effort
- Define maximum page weights
- Set Core Web Vitals targets
- Enforce budgets in development
- Reject changes that break budgets
- Focus on what users experience
- Core Web Vitals reflect real user experience
- Test from multiple locations
- Consider different device capabilities
Tools and validation
Google PageSpeed Insights:- Test individual pages
- Get detailed recommendations
- See real user data
- Validate GA4 findings
- Profile page loading
- Identify bottlenecks
- Test throttled connections
- Debug specific issues
- Test from multiple locations
- Detailed waterfall charts
- Compare before and after changes
- Filmstrip view of loading
Common questions
Why do my speeds differ from PageSpeed Insights?GA4 shows real user measurements from actual visitors. PageSpeed Insights uses lab data from simulated loads. Both are valuable but measure differently.
Should I prioritize mobile or desktop?Prioritize mobile. Most traffic comes from mobile devices, and Google uses mobile performance for rankings.
How long until improvements show in GA4?Usually 24-48 hours after changes go live. GA4 needs time to collect and process new measurements.
What's a good overall page load time?Under 3 seconds is good. Under 2 seconds is excellent. Over 5 seconds significantly hurts conversions.
Do slow pages always have high bounce rates?Usually, but not always. Highly valuable content may retain users despite slow loads. Still, faster is always better.
What's next
After analyzing site speed:
- Analyze engagement quality to see speed impact on engagement
- Review URL segments to find slow sections
- Check user paths to understand impact on navigation
- Test with PageSpeed Insights for detailed recommendations
Need help improving site speed? Use the chat widget in the bottom-right corner or email support@convertmate.io.