How to Diagnose Performance Issues in PageSpeed Insights?

A sluggish website is like quicksand for your business. Site slowdowns frustrate visitors, increase abandonment, hurt SEO rankings, and damage conversions.

But with over 100 potential factors impacting performance, where do you start troubleshooting issues?

Enter Google PageSpeed Insights – your site speed superhero.

PageSpeed Insights runs free diagnostic tests, pinpointing exact problems slowing your site. It then provides tailored tips to eliminate these performance killers.

Ready to whip your website into blazing fast shape? Here is a comprehensive guide to diagnosing and fixing PageSpeed issues step-by-step.

Why PageSpeed Insights Matters

PageSpeed Insights measures real user experience using key metrics like:

  • Server response time
  • Page load speed
  • Resource optimization
  • Image compression
  • Code efficiency

It then generates speed scores from 1-100 for both mobile and desktop.

  • 90+ = Fast
  • 50-89 = Average
  • 1-49 = Slow

Scores powerfully summarize how quickly your actual site serves content to visitors.

Top grades signal a well-optimized, lightning fast website. Low scores indicate slowdowns alienating visitors.

Since site speed impacts user experience, PageSpeed is a top ranking factor for SEO. Improving your grades directly lifts organic search traffic and conversions.

Let’s explore how to leverage PageSpeed Insights to diagnose exactly what’s slowing down your site.

Getting Started with PageSpeed Insights

Using PageSpeed Insights is simple:

  1. Go to
  2. Enter your homepage URL
  3. Click Analyze

This tests how your home page performs on mobile and desktop.

The overview tab shows your overall scores along with speed category grades:

  • Performance
  • Accessibility
  • Best Practices
  • SEO

Review the complete list of diagnostic opportunities to understand key issues hurting speed.

Now let’s walk through how to interpret results and take action on different performance problems.

Diagnosing Server Response Time Issues

The server response time measures how fast your server returns the first byte of content. This is shown in seconds under the PageSpeed score.

A quick server response time lays the foundation for overall fast page loads. Slow server response times delay everything else downstream.

If your server response time exceeds 200 milliseconds, further optimization is needed. Possible fixes include:

  • Switching to a faster web host
  • Enabling caching
  • Compressing content
  • Reducing redirects
  • Upgrading server software/hardware
  • Optimizing database queries
  • Minimizing plugins/extensions

Addressing slow server response time should be an early priority. This establishes the baseline from which additional speed gains can build.

Fixing High Priority Issues

PageSpeed Insights highlights high priority issues in red. These have the biggest potential impact on speed.

Some common high priority problems include:

  • Enabling text compression
  • Removing unused CSS/JavaScript
  • Reducing JavaScript execution time
  • Optimizing images
  • Leveraging browser caching for static assets

Tackle any flagged high priority items first. Gets these fixed before addressing lower priority optimizations.

High priority alerts provide the most direct route to dramatic site acceleration. They should always be the initial focus.

Diagnosing Individual Slow Elements

PageSpeed Insights lists how long each individual element takes to load on the page. Images, videos, JS files, and fonts are frequent laggards.

Pay attention to any items taking more than 1 second to load. These heavy elements bog down overall page speed.

Some ways to optimize them include:

  • Images: Compress and resize images. Convert large files to newer formats like WebP.
  • Videos: Use MP4 video codec. Reduce resolution if possible. Optimize with FFmpeg.
  • JavaScript: Minimize and defer non-critical JS. Check for duplicative libraries.
  • Fonts: Use font display options of swap or optional. Subset to load only needed characters.

Every individual element on the page contributes to overall load time. Diagnose heavy resources slowing things down, and optimize the worst offenders.

Checking Performance Categories

The PageSpeed Insights categories provide further speed diagnostics:

  • Performance – Page load time and speed metrics
  • Accessibility – Issues hurting users with disabilities
  • Best Practices – Common web development guidelines
  • SEO – Optimization for search engines

Scan each category for action items. For example, in Accessibility:

  • Adding ARIA roles for interactive elements
  • Labeling form inputs
  • Using legible contrast ratios


  • Adding meta descriptions
  • Specifying image alt text
  • Avoiding broken links

Review all categories to catch any quick wins. Properly structured and optimized code improves performance across the board.

Comparing Mobile vs. Desktop

PageSpeed Insights grades both mobile and desktop performance.

Pay extra attention to your mobile score – Google prioritizes mobile experience as most searches now happen on smartphones.

If your desktop score is significantly higher, look for issues hurting the mobile user experience like:

  • Resources blocking page load
  • Inefficient caching for mobile browsers
  • Too many redirects
  • Mobile-unfriendly elementos like small text or buttons

Optimize your site for mobile speed first given Google’s mobile-first focus.

Repeating for Additional Pages

So far this has covered diagnosing homepage speed issues. But understand performance across more of your site by repeating for other key pages, such as:

  • Blog
  • Pricing
  • Contact
  • Most popular product/service pages

This reveals if problems are isolated to just your homepage or are site-wide. It also shows which pages may be outliers underperforming the rest.

Regularly check a sample of pages to detect drops in performance over time before visitors notice.

Going Deeper with Developer Tools

PageSpeed Insights provides excellent high-level diagnostics. But developers can take troubleshooting even deeper using Chrome DevTools, Lighthouse, and WebPageTest.

These advanced tools allow drilling into details like:

  • File-level caching
  • Minified JavaScript and CSS
  • Individual resource waterfalls
  • Specific database and server optimizations

But start by quickly harvesting all the low-hanging fruit PageSpeed Insights identifies first.

Turning Insights Into Speed Improvements

The key to fast performance? Continually re-testing with PageSpeed Insights and iterating on enhancements.

Speed optimization is an ongoing journey, not a one-time fix. As you add features and content over time, keep diagnosing and improving.

With PageSpeed Insights, you have a powerful tool to analyze exactly why your site is slow, and how to fix it. Use these diagnostics to serve up lightning fast page loads that supercharge conversions and SEO.

Now that you know how to ace your next PageSpeed tests, it’s time take action! Follow this guide to pinpoint any performance pitfalls holding your site back, and unleash newfound speed to delight visitors in the blink of an eye.

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