I mean in `animateDrops` you check if `timestamp - lastExecutionTime < speed`. You set `speed` to 100ms when you call `engine.rain`. Because of this the motion

I mean in `animateDrops` you check if `timestamp - lastExecutionTime < speed`. You set `speed` to 100ms when you call `engine.rain`. Because of this the motion is jittery, updating at about 1/3 the rate of smooth video and 1/6th the rate our eyes can perceive.