Knowledge
WordPress, a CDN, and your images
A CDN makes your site faster by delivering files from locations closer to your visitor. But a CDN doesn't shrink your images; you get that benefit at the source, through optimization on your own server.
In short
- A CDN delivers faster, but doesn't compress
- Spark optimizes at the source, so your CDN caches lighter files
- Works with any CDN, without external image pipeline
What a CDN does and doesn't do
A CDN stores copies of your files in data centers around the world and delivers them from the nearest location. That shortens delivery time, but the file size stays the same as what you upload. An unnecessarily heavy photo stays heavy, just delivered faster.
Why optimizing at the source pays off
Spark Media Optimizer compresses and converts your images on your own server before they go to your CDN. Your CDN then caches the lighter version, so every visitor benefits twice: a smaller file and a short delivery time.
Because Spark doesn't require an external image pipeline, you stay independent of a separate service and the optimization works together with the CDN you're already using.
Tip: optimize first and then clear your CDN cache, so the old, heavier files are replaced by the new, lighter versions.
Compress at the source and let your CDN do the fast work.
Frequently asked questions
Not necessarily. Spark reduces the weight of your images, which already saves you something. A CDN adds speed in delivery, especially for an international audience.
Yes. Spark optimizes at the source, so your CDN simply caches the optimized files. You don't have to choose between the two.
No. Processing happens on your own server, without an external image pipeline, so you stay in control of your own files.