Speed Tests and ExactDN

Running speed tests (like PageSpeed Insights, WebPageTest, Pingdom, etc.) on your site can be a good way to waste days of your life. There, I said it, now let's move on...

Seriously though, if you've never used a CDN, there is one important thing to know. A CDN has a lot (hundreds) of servers, and each one of those has to fetch a copy of your images. That only happens as quickly as real people view your page (from the location nearest each of those servers). We call this process filling the cache.

While each optimized image is stored on our central caching system to try and speed up this process, if you run a speed test the instant you enable ExactDN, you're going to be disappointed. So, what in the world should you do?

We recommend that you use GTmetrix to test the speed of your site, for several reasons:

  1. GTmetrix lets you choose the location to test your site. This means you can consistently test your site from the same location, and it will build up the CDN cache for that location more quickly. I always use the Dallas location, because there are sometimes routing issues with the default Vancouver location that cause images to be transferred from the other side of Canada.
  2. When you go to the Waterfall tab, you can actually see if GTmetrix is getting cached results, or if the cache is still being filled up. What? How? Tell me quick! Alright, alright, slow down :) Scroll down the waterfall view, and look for files that were loaded from ExactDN (you know, the ones with .exactdn.com in the url). Click on one, and look for "Cache:" in the Response Headers. If it says MISS, run the test again. If it says HIT, check a few others. If you find any misses, run the test once more.
  3. You can get a free GTmetrix account to view some useful stats on the Timings tab. Fully Loaded means EVERYTHING has finished loading. It does not necessarily line up with when the page appears to have finished. So if you're using anything clever to defer resources or load them in async mode, especially things like ads, the fully loaded time might paint a dismal picture. But never fear, check the Contentful Paint and Dom Interactive times to see when the page actually shows up for the visitor.

Even better, go load the page yourself. Of course, make sure you logout first, so you get the same experience as your visitors. Do it on a laptop, on a tablet, on a phone, any device you have, do some real tests and see how it feels. If it doesn't seem fast enough, sure, go run the tests to see what you might be able to improve.

Otherwise, go get some coffee (or your beverage of choice) and just relax. Then go spend more time working on what you enjoy!

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