August 23, 2015

Favicon compression

Posted on August 23, 2015  •  3 minutes  • 570 words  •  Suggest Changes

While checking speed using, I noticed the favicon I created was 97,3 kB large. Now that “only” contributes to 386ms load time (62ms initial, 72ms ttfb and 252ms content download).  I thought that was pretty oké, until I checked out yet another service that checks common speed issues. (zoompf) Generally I distrust commercial products as they always claim to make your server run 10x as fast if you just buy there product.  Similar numbers popped out of the free result : The favicon could be compressed and up to 91% “faster”.

So I googled around and found a nice article, but sadly its for Mac claiming up to 60% smaller file size without sacrificing quality. Lucky for my wallet, I don’t own a Mac and the suggested tools don’t work with windows all that well. So I tried to upload and “auto create” an ico. The result was acceptable and the download of my favicon was only 1,12 kB large anymore !

Now I started jumping around. With some more googling however, I found that the original large .ico is in fact a container for multiple images (in my case 5) that will be picked by the browser depending on what the browser likes best. (cheat sheet on favicons)

So back to zero ? Not really, in my hunt to find a service that could make compressed ico’s for me I found favicomatic. A great service that picks up my original png file (5,64 kB) and makes all kinds of formats. (including the code I have to copy & paste!)

favicon-16x16.png, 1kb
favicon-32x32.png, 2kb
mstile-144x144.png, 8kb[/table]

While allot more then the’s 1,12 kB still a reduction from 97,3 kB (note: not all of them get downloaded, just the one the browser likes best)!

Now kB’s don’t say much when you don’t know how much ms’s I just shaved off.

download,97.6 KB, 0.8 KB
time,252 ms, -
Using, who selected favicon-16x16.png. As seen in the table, the ms is not given, considering (97,6/252) x 0,8 =~ 0.3 ms it seems that the download time is trivial <1ms and as such is not given. (from the Brussels datacenter of webpagetest, the website is located on an Amsterdam datacenter)


Favicons are the tiny little things in the browser, that get loaded when you visit a site, they also show up in front of the bookmark. So its useful to set up a nice one. While digging I found that the ico I used was rather large, and that is not really needed. So I down scaled it using different services, of which I liked the most.

While checking how much speed I had gained, I noticed that google’s builtin development tools (control-shift-I) din’t show favicon.ico. So I  cannot reliably say how much speed I have gained, if I even have gained speed, as ico’s generally get downloaded only once, and I had to add html code to support multiple files for Apple devices and w10’s edge browser.

The however gives me a better score and in no way 3 lines of html equal 97kB of ico. So I think I made some gain, I doubt users will notice the 250ms difference, but on a bad server day it might make some difference ! The key to a faster website obviously is in tiny steps!


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