Transition test

Testing with a a Dell Win7 Celeron netbook doing 120 sprites and checking Task manager. Note that the JavaScript code is unoptimized (e.g. we repeat the sin/cos calculations every cycle, when we could store them), but I'm guessing/hoping that the CSS transitions are the main CPU hog. The 'flipping' code takes between 2-6 milliseconds (*depending on browser), once per second - that's less than a frame at 60hz, so it shouldn't have any noticeable impact

Testing with no background image:

• Chrome (Iron actually) 6 reaches 30-40% CPU
• Safari uses 50-65% CPU.
• Minefield (Firefox 4 beta) uses >80% CPU and is definitely jerky.
• Opera uses <20% CPU, but (non-scientific opinion here) looks a bit jerkier

Testing with a scaled JPEG background

• Chrome/Iron: >60% CPU, and causes parts of the background to judder (doesn't happen on unscaled background)
• Opera takes over 50% CPU, but it otherwise fine
• Safari 5 takes >70% CPU, but is otherwise fine
• Minefield is only marginally higher CPU than without a background