For the most part, this addon runs seamlessly in the background, not being intrusive at all... it even works with links from other applications, like your desktop email client!

However, it does cause a hiccup on some sites, like pinterest, causing the browser to run into an endless reload loop, often disabling page functionality. This affects every other tab you try to switch to, and only stops when the offending tab is closed and then the other tabs are refreshed or sent back a page, or the entire browser is restarted.