I'm running a gtmetrix.com report against my site. I get an F(41) for gzip compression. I don't own the two problem files mentioned for this penality.

One file is a CSS on Mailchimp's server. Another is a javascript file that can't be gzipped compressed. When that JS file is compressed, it breaks on-page javascript calling into the file.

I can understand being penalized since I'm calling these files. But if I want to use Mailchimp and the JS file, does that mean I will always be penalized since there isn't a way around these issues.

It's likely my site would go from 85% (B) to an A if I could resolve the above two issues.

I did try moving the mailchimp file to Amazon S3 and enabling gzip. But for some reason, the browser is unable to GET the file with gzip enabled:

(from Google Chrome developer tools) enter image description here

Any ideas why that happens with gzip?

  • Sounds like gzip is not enabled for CSS files on that server. Why don't you put it on your server if you copy it anyway? Do you use static or dynamic compression? Hard to believe that JS does not work with compression. That is browser stuff; JS should not even see that. Apr 16, 2013 at 3:44
  • I can't put it on my server because I'll be penalized by the report. I'll ask Amazon about gzip for CSS.
    – 4thSpace
    Apr 16, 2013 at 4:02
  • You get a penalty for not putting static content on a seperate host? Apr 16, 2013 at 4:05
  • For not putting it on a CDN.
    – 4thSpace
    Apr 16, 2013 at 4:24

2 Answers 2


You can't just go and change the configuration of someone else's server. So unless MailChimp decides to start gzipping these files, there's nothing you can do but complain to them until they do.

  • In the above put, I copied MailChimp's CSS file to Amazon S3.
    – 4thSpace
    Apr 16, 2013 at 4:01

Even if you cannot enable compression on the Amazon server you can still get the feature: You put a (e.g.) PHP script at that URL and have the script check the HTTP request for compression support. Depending on that it sends either the compressed or the uncompressed file.

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