It provides a way for developers to communicate with each other in a developer channel.

Wouldn't it be both exciting and useful to be able to open the console of nearly any site and immediately get a link to the code or author on GitHub? Sometimes these sorts of links aren't appropriate on the site itself, especially in the case of contract/client work.

That being said, performance is very important. Which is why we kept Signet small. signet.min.js (https://github.com/HubSpot/signet/blob/master/signet.min.js) is 5kb (smaller if gz) and has no dependencies.

As one anecdotal data point: I recently added Signet to my personal site and it had no impact on page load time.