I did a quick Google search and discovered that SVG favicons are valid in most browsers, so for fun I reduced it by 95% down to 886 bytes:

https://output.jsbin.com/yudonidujo

And it looks much nicer zoomed in (as in your link) ;)

svgo got it down to 876 bytes without visual difference but svgcleaner couldn't do anything.

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 48 48"><path fill="#662113" d="M27.3 5.7c4.9-3.1 11-3.9 16.8-4.1A162 162 0 0031 10l-3.7-4.5zm4.1 5.6c4.8-3.6 10.1-6.5 15.3-9.6a18 18 0 01-4.3 12.7l-11-3z"/><path fill="#c1694f" d="M44 1.6l3.3-.3-.6.4c-5.2 3.1-10.5 6-15.3 9.6 3.7 1.2 7.3 2.2 11 3l-6 6.2c-3.6-.8-7.4-2.8-11-2.4a70.5 70.5 0 00-17 18.3c2.7.2 5.5.4 8.2.4h.5c-3.3.2-6.6.4-9.9.9 3.6.6 7.2.5 10.8 1-3.7 2.2-8.2 1.7-12.4 1.7-1.6 2.4-2.7 5.3-5 7.1.7-2.8 2.6-5.2 3.8-7.8.1-2-.4-4.1-.5-6.2L6.7 36l.3-.3c5.2-7 10.7-13.7 17-19.7l-1.6-7.7L27 5.4l.3.2 3.6 4.5c4.3-3 8.7-5.9 13.2-8.5z"/><path fill="#d99e82" d="M8 21.2C11.6 16 17 12 22.3 8.3L24 16A178 178 0 007 35.7c-1-4.8-1.3-10 1-14.5zm.5 15.2c4.6-6.8 10-13.4 16.8-18.3 3.7-.4 7.5 1.6 11.1 2.4L33 24.1c-2.5-.2-4.9-.4-7.4-.4l5.4 2.4-3.2 3.5c-3.7-.3-7.4-1-11.2-1l9.7 3a10.7 10.7 0 01-9.5 5.2c-2.7 0-5.4-.2-8.2-.4z"/></svg>

Nicely done. Manual or automatic conversion?

[1] generates ico, png and svg. you may want to remove some favicons from the generated HTML snippet; in my brief testing, Firefox loads both png and svg, while Chrome loads ico.

[1]: https://realfavicongenerator.net/

excellent. have you shared this with the website person and asked them to use this ?

I recently noticed something similar, while optimising my e-commerce website.

I went with:

  <link rel="icon" href="data:;base64,AAABAAEAEBAQAAEABAAoAQAAFgAAACgAAAAQAAAAIAAAAAEABAAAAAAAgAAAAA
  AAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
  AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
  AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
  AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA">

Renders a black square, everywhere except Safari. The black square actually goes with the brand.

Doesn't it support RLE compression?

What kind of an internet connection are you on that 15kb is significant?

Performance is important, but if your site is clocking in at 17kb then you're probably doing okay.

But when you start this way, you quickly endup with the bloat that is modern software. Because each extra bit of waste seems justified at every steps along the way.

May seem pedantic but those little gains do add up. A missing favicon also has a surprising impact.

Spoken like somebody who's never been to Antarctica. Or on a slow train WiFi for that matter...