HTML5 Audio() Timing / UI Jank Test

Calling play() on HTML5 Audio() instances causes stuttering and UI responsiveness issues on Safari 7.0 (9537.71) and Webkit nightly on OS X 10.9 (November 2013.) An .mp3 of 0.444 seconds is used for this demo.

Jank appears to relate to the number of actively-playing instances. Each square represents a sound object.

Firefox remains responsive, but timing of audio playback is somewhat inconsistent on OS X. Chrome is smooth through 60 fps. IE 9 runs nicely at around 48 fps on a test VM.

See bugs.webkit.org #116145.