Oddly, it use 100% of one of my i7 iMac core when running on Chrome (6.0.408.1). However, the animation play very smooth with only 1~2% CPU usage when running o

Oddly, it use 100% of one of my i7 iMac core when running on Chrome (6.0.408.1). However, the animation play very smooth with only 1~2% CPU usage when running on Safari (4.0.5 6531.22.7). So I assume you're using Chrome? Edit: -webkit-animation in general seems to be very slow in Chrome. Edit again: Oh right, -webkit-animation is hardware-accelerated in Safari. http://webkit.org/blog/324/css-animation-2/#comment-25071 http://webkit.org/blog/324/css-animation-2/#comment-25071