CDN Proxying Third-Party Scripts To Improve Website Performance


Third-party scripts slowing you down? Speed things up by using a CDN proxy!

As we recently worked to optimize a client site, Google PageSpeed Insights had a number of suggestions for us, including “Leverage browser caching” and “Enable compression“.

The only problem? These suggestions were triggered by a third-party javascript file that was important to website performance. We couldn’t affect the script cache or compression settings because the script wasn’t hosted by us. We didn’t want to host the script either, because the vendor occasionally updates their script and we need those updates to be reflected on the site.

How could we easily fix the cache and compression settings of someone else’s script while continuing to automatically serve new versions of the script when it is updated?

We were already using a CDN on the site—so we decided to try using the CDN to proxy the script.

We set up a new pull zone because we wanted specific settings just for this file. We set the origin URL to be the domain name serving the third-party script. Using the CDN settings, we were able to have the CDN apply GZip Compression and override the default cache headers.

Cache Settings

The last step was to update the website to access the script from the CDN instead of directly from the vendor.

Voilà! We were now serving a compressed and cacheable version of the script to our clients, who would see updates to the script within a day. Google PageSpeed Insights complained less about our site, and the site loaded more quickly for visitors.

CDN Before

Before: Third-party scripts can bottleneck your page load time

  CDN After

After: A CDN proxy can remove third-party bottlenecks

There are a dozen ways to optimize your website or web app performance.  Stay tuned for more in our new “Better Website Performance” series.


Steve Hulet


Steve is the Co-Founder and CTO at Fresh. A former Software Engineer at Amazon with over 12 years of web development experience, Steve provides technical, architectural, and engineering oversight to projects. Steve is responsible for all technology reviews related to websites. His specialities include programming languages such as C, C++, Java, Python, and PHP, and technology software including Eclipse, GLPK, jQuery, Linux, and MATLAB. Steve’s skills include automation, databases, linear programming, optimization, and testing, all of which he uses in conjunction with Fresh’s digital strategists provide innovative solutions to clients.