Slow Time to First Byte (TTFB) Using Custom Domains

Two websites I own use custom domains that were registered with another registrar and the nameservers were changed to Netlify’s. I’ve conducted tests using on both of the websites and their time to first byte (TTFB) resulted in a score of C. If I test the website again using the [subdomain] domains I achieve a TTFB score of A.

Is this normal behaviour or may I be missing something? Thanks.

Hey @pavsidhu,
Could you please share the custom domains or the Netlify urls associated with them? Then we could check out your DNS setup and make sure all looks good there.

Yeah of course, the domains are and

hey there, we are still taking a look at this and haven’t forgotten. We’ll get back to you soon.

Appreciate your help, thanks!

Hey @pavsidhu,
Thanks for your patience on this! We looked at both sites- your DNS is set up correctly :tada: so then we looked in our logs at response times. TL;DR, we didn’t see anything unusual with your site or load times. With page speed tools like the one you used, we’d recommend testing twice from the same location, since the part of Netlify’s architecture that makes sites fast is that users load from our CDN nodes around the world… but the site has to be in the node cache first in order for it to load quickly for other visitors.

More details if you want them: our logs for show that the average response time over the last week was ~209ms, which we think is reasonable. The slowest, but still pretty fast, times for that site were ~1.5s and those requests were for assets that were not cached in our CDN nodes, so they had to make a round trip to our origin in SF from (mostly) Australia.

The story with is a little more interesting. For most of the last week, response times have been ~870ms. We think this is a bit slower than your other site because it includes some large (> 2MB) images. There were a few outliers though that took more than 20s to load! These requests were concentrated in two “events” lasting less than an hour each and the user-agents were all mobile phones. We think those load times were due to loading big assets over mobile networks, which are less reliable.

Hope this helps! If you continue to see slow timing, please come back and let us know and we’ll see what we dig up.

Ah okay that’s really useful, so nothing too much to worry about in terms of the DNS, but still things that I can improve my end. Appreciate your help with this thanks!

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