[GoToRO]

Cool! when tab is not active, the rhythm slows down in Chrome/win7.

[nprescott]

This is due to a step taken by the browser to improve performance, namely, timers in Chrome are limited to 'ticking' at most once a second when a tab is backgrounded. The drum loop is at its core:

    setInterval(function() {...}, 1 / (4*BPM/(60*1000)));

https://codereview.chromium.org/6577021