What is PageSpeed?

It is a tool that optimizes and implements for you the best practices of the web according to Google. It rewrites your website to make it faster for your visitors. It’s automatic and transparent.

It allows to:

  • “Minify” HTML, CSS and JavaScript (remove comments, unused code etc …)
  • Rewrite the images to lighten their weight
  • “Defer” the JavaScript (ie run the JS when the page has finished loading before)
  • Remove white spaces
  • Caching on the RAM
  • Rewrite CSS and JavaScript optimally
  • and more! See the full list at

Which rules should I activate?

When you enable PageSpeed ​​from your World or cPanel control panel, the recommended rules are enabled, commonly called “CoreFilters“. These are widely used rules and are suitable for most websites.

On the “Advanced” section, you can choose more advanced rules. To do this, click on “Configuration”, then “Advanced” and choose the desired rules. We recommend that you consult the official PageSpeed ​​documentation to learn more about each rule and its usefulness.

How to debug in case of worry?

The tool allows a clear and simple debug.

To do this, simply navigate to your favorite browser and then add the debug parameter. See the example below:

Then open the source code of the page. You will see several debug comments and at the very end you will see a block similar to

mod_pagespeed on
ah  Add Head
cc  Combine Css
jc  Combine Javascript
gp  Convert Gif to Png
jp  Convert Jpeg to Progressive
jw  Convert Jpeg To Webp
mc  Convert Meta Tags
pj  Convert Png to Jpeg
ws  When converting images to WebP, prefer lossless conversions
db  Debug
ec  Cache Extend Css
ei  Cache Extend Images
es  Cache Extend Scripts
fc  Fallback Rewrite Css
if  Flatten CSS Imports
hw  Flushes html
ci  Inline Css
ii  Inline Images
il  Inline @import to Link
ji  Inline Javascript
js  Jpeg Subsampling
rj  Recompress Jpeg
rp  Recompress Png
rw  Recompress Webp
ri  Resize Images
cf  Rewrite Css
jm  Rewrite External Javascript
jj  Rewrite Inline Javascript
cu  Rewrite Style Attributes With Url
cp  Strip Image Color Profiles
md  Strip Image Meta Data
CssInlineMaxBytes (ci) 32768
EnableRewriting (e) 1
ImageInlineMaxBytes (ii) 32768
JsInlineMaxBytes (ji) 32768
RewriteLevel (l) Pass Through
RunExperiment (fur) False
#NumFlushes            0
#EndDocument after     1273us
#Total Parse duration  1249us
#Total Render duration 6797us
#Total Idle duration   24us
No critical images detected.
The following filters were disabled for this request:

Finally, to compare the result with PageSpeed ​​and without PageSpeed, just add the parameter that disables PageSpeed:

Updated on 18 August 2021

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