Site loading much faster after turning Developer mode on

Hi Cloudflare Community,
We have been struggling to troubleshoot our site performance during peak visit days when we have dramatically greater numbers of visitors We tried turning off Cloudflare caching temporarily by turning on Developer mode. The site immediately began to perform noticeably faster although we could see the increased load on our web host server. The strange thing is that when Developer mode turned off, after about three hours, the performance enhancement for our site remained. Can anyone give me a clue about why that might be the case?

Thanks in advance.


In retrospect this is difficult to impossible to say.

My most likely guess would be you had some error in how you measured it. My next best guess would be it might have been some coincidence with some network issue along the route.

Other explanations could be that you still had an earlier version of site cached (JavaScript for example) which performed less efficient than its newer version. Of course there is also the possibility of Cloudflare having had some temporary issues, though I’d rather rule that out.

Thanks for your response. Would turning on dev mode flush some sort of Cloudflare cache? Are there settings that would tell me that somewhere?


Development mode generally turns off the cache. Whether any entries are flushed or persist and are back once caching is back on is something I cant tell right now.

Respectully, your response does not help me figure out what has changed. A developer on our team who works remotely also noticed how quick our web site response has become. This tells me that this has nothing to do with our own network changes. We have also not made any major changes to JavaScript in a many months and our speed before this event was consistent. If anyone else on this forum has any ideas I’d love to hear them.

No. By itself, turning dev mode does not flush the cache. Some (or even all) of your files may have expired, though, during the 3 hours you left dev mode on, depending on your Edge Cache TTL (or the cache headers set at your origin server) and how long ago the cache was created. Edge Cache TTL is a setting available on Page Rules.

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I already addressed that in my very first response. With the information provided so far it is impossible to say anything at all. We have no URL, we have not definition of “perform noticeably faster”, we have nothing I am afraid. Are we supposed to guess? Your description actually is the opposite of how things typically work. Cloudflare’s caching decreases loading times, not increase them.

As for your second question, I have already answered that and @cbrandt posted some further clarifications.

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