I am trying to optimize the following page: https://123tinki.com/nl-nl/c/geperste-hondenbrokken

It is served by an NGINX reverse proxy. Static content like .js and .css is cached by the NGINX server. The first ~30 recources seem to download fine. They have a TTFB of ~20 ms. But then suddenly TTFB rised to ~500 ms. If I load the resources individually in a new window, they have a normal TTFB. I checked the response headers on the resources and they are served from the NGINX cache (x-proxy-cache: HIT).

enter image description here

Why is the TTFB so slow? Maximum parallel downloads does not seem to cover the issue. In that case I would assume the download would start after the previous downloads finished. How can I investigate?

  • That is a lot of resources to load for a single page view. Seems like a lot of opportunity to combine JS and maybe do sprites or data:image URLs for smaller images. May 15, 2019 at 1:27

1 Answer 1


Of note, the "Time" column in Chrome measures the total download time of the resource until the last byte, not the time to first byte. I would guess that the JS files are taking more time to download just because Chrome is focusing on loading the CSS and PNG files before the JS, because they are render-blocking.

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