High performance favicons (updated 2012-04-16)

Date: 15 Mar 2012
Author: Erik Dubbelboer

For my company we have an ad-server which handles hundreds of connections per second. Many of those are HTML iframes for ads. It doesn’t really make sense for those pages to have a favicon but we noticed that many browses still request favicon.ico. This only ads load to our already busy server so we place the following code in our iframe HTML:

<link rel="shortcut icon" href="data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==">

This is the smalles possible image in a data url. A 1x1 gif. Even though data url’s aren’t support in IE versions before 9 we hardly notice any requests for favicon.ico anymore (Maybe IE doesn’t request favicon’s for iframes?).

Update 2012-04-16

Some days ago I had the idea for a even smaller favicon, namely about:blank

<link rel="shortcut icon" href="about:blank">

I have tested all the options for a couple of days and collected the following data:

No favicon in the html

6752 requests per hour.

  • 48% Chrome
  • 42% Firefox
  • 10% IE


252 requests per hour.

  • 50% Firefox
  • 22% Opera
  • 15% IE
  • 13% Google Desktop

Data URL

106 requests per hour.

  • 100% IE
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