mod_pagespeed and WP Super Cache issues

Dreamhost recently showcased their mod_pagespeed “switch” that was made available for all of their hosting customers, so I took a stab at enabling it. Most of my websites run WordPress which already isn’t exactly the quickest CMS so I figured I could use all the help I could get to make the pages load quicker.

One plugin that many WordPress users, myself included, use is called WP Super Cache, which basically caches your website as HTML instead of PHP to minimize processing delays in displaying your website to your visitors.

One option that the plugin gives you, is to gzip compress the HTML to send to the viewers. At this time, it looks like using mod_pagespeed and enabling the “Compress pages so they’re served more quickly to visitors” option in WP Super Cache will break your website. I’m not sure at the moment why this is, but if I have this enabled, both FireFox and Chrome error out when loading websites with a content encoding error, saying the content encoding on my website is incorrect.

On a side note, once that option is turned off, mod_pagespeed works great!

Anyone else having this problem?


  1. [...] This post was mentioned on Twitter by CreativeBoulder, Andrew. Andrew said: mod_pagespeed and WP Super Cache don't play nicely #dreamhost [...]

  2. Saw you mentioned this on twitter – it’s definitely been playing a pretty harmful roll with some of my blogs. Thanks for the heads up!

  3. Interesting. I’ll have to install mod_pagespeed and figure out how to detect if it is compressing pages.

    Unfortunately, if mod_pagespeed compresses a page each time they’re served that will slightly increase CPU usage. Supercache stores the compressed page so gzipping is only done once.

    • Andrew Peng says:

      exactly my thoughts – DreamHost is currently researching what to enable and what not to enable in their mod_pagespeed system – I’ll let them know to see if they can disable any sort of “gzipping” in the output stage so we can leave that up to the code

  4. Townend says:

    We’ve been having problems with it crashing the server actually, got a lot of trawling through the error log to find out why. Put a quick performance review together before that started though: mod_pagespeed review:

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