Slow download speeds on Netlify CDN


In the last week or so, we’ve noticed fairly slow transfer speeds of our JS scripts (~ 5MB file) from the Netlify CDN. When we self-host the website in a Docker container, I get about 2 Mbps download speeds. On the other hand, the Netlify equivalent shows 350 kbps. We’ve even tried after a while to ensure that the CDN was warmed up and the assets cascaded (hopefully).

Any particular reason that this could be happening? Anything that we can do at our end to resolve this?


hi there, sorry to hear you’ve been seeing what seem like slow download speeds :confused:

Can you tell us what sitename this is related to? Also, it would be incredibly helpful if you were able to provide us with a HAR file we can analyze:


Thanks for your response Perry.

Out sitename is The x-nf-request-id for the slow request is: 58f49a55-0160-47fd-99d9-2ce2ebf1cbd8-1654324.

I’ve also attached a HAR file if you think that would be more useful.

Appsmith HAR File


Thanks for that data!

Interesting - our CDN’s internal logs show that we finished sending that file (from the request that you gave me the x-nf-request-id for) 5ms after the request was received, so the slowness is definitely not expected or seen from our side. Thanks for preemptively sending the HAR file since that would have been the next question :slight_smile:

The HAR file shows that file downloading (in a separate request), in 522 milliseconds:

Considering that you fetched the file from India, and our nearest CDN node is in Frankfurt or Singapore, I’m not surprised it took a moment to get to you. 522ms isn’t really super slow for that kind of transfer. That’s a lot faster than your “350kbps” which by my read would make that 1.5MByte file take either 4 seconds or 32 seconds depending on whether you meant kilobits or kilobytes. Seems to me it transferred at almost 3MByte/sec.

However, now that I know the domain, I can look across all accesses in our logs and I do see some rather slow loads including one that goes from US<->US, so I’ve asked our operations team to look into this a bit further for us. We’ll get to meet with them next wednesday and will get back to you thereafter!

Thanks a lot for your response. Appreciate the help in debugging this problem.

Looking forward to the response from the operations team.


I just wanted to follow up and find out if you had a chance to talk to the operations team about this issue. Any idea how we can resolve this issue?

still working on it, @arpit! we haven’t forgotten, promise. more soon, thanks for your patience.

Hi, @arpit, I’m also showing this HTTP request traveled from India to New York instead of traveling from India to Singapore. This is also probably a large factor in the slow performance.

I think the DNS service being used is sending you to the wrong CDN node.

What DNS service are you using? In other words, what is the IP address for the DNS server for the system which made the HAR file?

Hey Luke

Our DNS is hosted on AWS Route53. All the static assets are served by Netlify itself. While the dynamic data is fetched by invocations to our API server in Ohio (us-east-2).

Does this help answer your question?

Hi, @arpit, actually I’m talking about a different DNS server.

I am not asking about the authoritative name server for this domain.

What I am asking is this:

  • What is the name server used as the DNS resolver for the system that made the HAR file?

For example, the laptop I am using to write this uses the two IP addresses and for DNS lookups. I’m looking for this same information for the computer that made the HAR file.

I suspect that computer may be using If so, changing this should resolve the issue.

Edit: Here is another example of a similar report.

Hey Luke

Sorry for the late revert here. I forgot to reply.

Thanks. Yes, my computer was using as the DNS resolver. Changing it to did help.

Closing this issue from my side for now.

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