Home/ Questions/Q 3878542
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-19T22:37:28+00:00

I have read that combining all of your css files into one big one,

  • 0

I have read that combining all of your css files into one big one, or all of your script files into a single script file reduces the number of HTTP requests and therefore speeds up download speed.

But I don’t understand this. I thought that if you had multiple files (up to a limit, which is 10 I believe on modern browsers), the browser would download them in parallel, thus REDUCING the total time to download (divided by the number of connections allowed).

I am obviously missing a key piece of info here. Can someone turn on the lights?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    There’s overhead in every request/response. That’s essentially what it comes down to.

    Here’s an example of a request header to Google …

    GET http://www.google.com/ HTTP/1.1
    Accept: application/x-ms-application,
    image/jpeg, application/xaml+xml,
    image/gif, image/pjpeg,
    application/x-ms-xbap,
    application/vnd.ms-excel,
    application/vnd.ms-powerpoint,
    application/msword,
    application/x-shockwave-flash, /
    Accept-Language: en-US User-Agent:
    Mozilla/4.0 (compatible; MSIE 7.0;
    Windows NT 6.1; WOW64; Trident/4.0;
    GTB0.0; SLCC2; .NET CLR 2.0.50727;
    .NET CLR 3.5.30729; .NET CLR
    3.0.30729; Media Center PC 6.0; OfficeLiveConnector.1.4;
    OfficeLivePatch.1.3) Accept-Encoding:
    gzip, deflate Connection: Keep-Alive
    Host: http://www.google.com Cookie:
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

    I wrote an article about this last year…
    http://swortham.blogspot.com/2010/03/latency-requests-css-sprites-and-you.html

    You are right that multiple files can be downloaded in parallel (2 or more from a single hostname, depending on the browser). And that in turn will cause the page to load progressively, which is good. But that doesn’t mean that your homepage should be composed of 20+ css, js, and image files. Ideally you’d want to combine quite a bit to optimize the site.

    • 0