Drupal 7: How to get a high pagespeed score

Install Advagg module bundle
Activate Advanced CSS/JS Aggregation (AdvAgg)
Activate AdvAgg Modifier

Go to admin/config/development/performance/advagg

Check "Use customized settings"
Uncheck "Use cores grouping logic"
Check DNS Prefetch and Preconnect under Resource Hints
Check "Combine CSS files by using media queries"

 Install AdvAgg Modifier if not enabled and go to admin/config/development/performance/advagg/mod

• Check "Enable preprocess on all JS/CSS"
• Enable every checkbox under "Optimize JavaScript/CSS Ordering"
• Under "Move JS to the footer" Select "All but what is in the $all_in_footer_list"
• Under "Deferred JavaScript Execution: Add The defer Tag To All Script Tags" Select "All but external scripts"
• Check "Put a wrapper around inline JS if it was added in the content section incorrectly"

Compress Javascript if not enabled and go to admin/config/development/performance/advagg/js-compress

• Select JSMin if available; otherwise select JSMin+