Extension allows user to see loading time based on performance api's getEntries() method
It is based on message passing in chrome. Apis are based on performance.getEntries() & are linked below. You can also obtain more information by using performance.getEntries() or performance.timing.
Note: Extension does not require any permissions from the users.
-http://blog.trasatti.it/2012/12/measuring-the-speed-of-resource-loading-with-javascript-and-html5.html
-https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/browserAction/setBadgeText