WordPress CDN Performance: When Edge Delivery Helps
A practical guide to using CDNs for static assets and, where appropriate, cached HTML.
Short answer: A CDN can reduce network distance by serving cacheable resources from edge locations. The benefit depends on audience geography, cacheability, origin performance and what the CDN actually caches.
A CDN does not replace origin optimization when content frequently misses cache.
Static asset delivery
A CDN does not replace origin optimization when content frequently misses cache.
For a worldwide audience, distributed delivery can reduce latency, especially for static assets.
- Change one important variable at a time.
- Compare repeatable behavior rather than one isolated score.
- Keep reliability and maintainability ahead of marginal benchmark gains.
Edge HTML caching
For a worldwide audience, distributed delivery can reduce latency, especially for static assets.
Keep purge behavior predictable so content updates do not get trapped behind stale edge responses.
- Change one important variable at a time.
- Compare repeatable behavior rather than one isolated score.
- Keep reliability and maintainability ahead of marginal benchmark gains.
Cache keys
Keep purge behavior predictable so content updates do not get trapped behind stale edge responses.
A CDN does not replace origin optimization when content frequently misses cache.
- Identify which layer is caching the response.
- Prefer the narrowest safe purge instead of clearing every cache by default.
- Verify behavior while logged out or in a private browsing session when testing public page caching.
Purges
A CDN does not replace origin optimization when content frequently misses cache.
For a worldwide audience, distributed delivery can reduce latency, especially for static assets.
- Change one important variable at a time.
- Compare repeatable behavior rather than one isolated score.
- Keep reliability and maintainability ahead of marginal benchmark gains.
Origin shielding
For a worldwide audience, distributed delivery can reduce latency, especially for static assets.
Keep purge behavior predictable so content updates do not get trapped behind stale edge responses.
- Change one important variable at a time.
- Compare repeatable behavior rather than one isolated score.
- Keep reliability and maintainability ahead of marginal benchmark gains.
Global audiences
Keep purge behavior predictable so content updates do not get trapped behind stale edge responses.
A CDN does not replace origin optimization when content frequently misses cache.
- Change one important variable at a time.
- Compare repeatable behavior rather than one isolated score.
- Keep reliability and maintainability ahead of marginal benchmark gains.
Practical decision rule
Fix the layer the evidence points to. Caching helps repeated server work; CSS and JavaScript work affect rendering and responsiveness; images and fonts affect transfer and discovery; hosting and application behavior affect origin response. Avoid solving a different problem just because a tool is popular.
Related guides
Sources and further reading
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