How can I tell Chrome to use all 6 concurrent connections asap?

Question

I would like to improve rendering performance of http://www.camping.info/campinplaetze. Running a test on WebPageTest.org I see in the waterfall chart that for images loaded from http://images-camping.info, Chrome initially opens only three connections, and only at the 2 second marks opens another three. That's why the first 6 images are loaded consecutively, all on the third open connection as seen in the connection view:

I would like Chrome to open the six concurrent connections to images-camping.info around the 1 second mark so that it could download more images in parallel which I assume would make rendering the page faster.

Does anyone know of a way to do that?

Solution 1

Short Answer - every browser has a specific limit to open parallel connections. In the case of Chrome this limit is 10.

If I was there, I would do only two things:

1. Optimize images - If you're using png files, then I suggest to use tinypng.com, because it compresses images well, compared to Google PageSpeed module.

2. Serve Images from CDN - Use Amazon Cloudfront CDN to serve images, because image URL begin with Amazon Cloudfront URL, so you don't need to use second domain, here is an example of how they serve images with their domain name. CDN helps in many ways.

Solution 2

You can have several subdomains (CNAMEs) and load some resources via them, eg:

• css.domain.com
• js.domain.com

or, better, assets1, assets2 etc. They all point to the same server, but in your page sources you use different subdomains to trick the browser around

Comments

[Andrew Lott]

Running HTTP/2 will probably give you an even better pipeline for serving multiple resources.

[Oliver]

It's probably time to turn this on in our NGINX server...

[Oliver]

From you link I can see that Chrome uses only up to 10 parallel connections - this explains my observations perfectly. Thanks also for the other tips.