Apache 2.2 and beyond. Beta since 2012, 1.0 version in 2013?
MD5 hash of combined file names for caching, e.g. if content changes a new hash is generated.
Apache mod_pagespeed Overview
Optimizing your Web Performance with
What Is Mod_Pagespeed?
“mod_pagespeed is an open-source
Apache module created by Google to help
Make the Web Faster by rewriting web
pages to reduce latency and bandwidth”
What it Does
“Performance JIT” to automate 40+ performance best
Caching Combine CSS
CSS to Head
• “Core Set” of “safe” optimizations
– Combine CSS, Compress Images, Minify, etc.
– Turns on mod_deflate (Gzip compression)
• Optional filters for potentially disruptive improvements:
– Move CSS to head
– Convert PNG to JPG
– Remove HTML comments
– Sprite Images
How it Works
• Great (long) youtube video
– Skip to ~22 minute mark for Apache filters
• Apache input & output filters to rewrite content
• Based on pagespeed libraries (not Apache specific)
• CPU intensive operations offloaded to background
– Optimize on first use
– Examples: image compression, resize images
• Per-request testing
• A/B testing w/ Google Analytics
Use different filters for different % of traffic, different
• Mapping sharded domains to mod_pagespeed