Jit.slide

Jit.qt.record does not maintain its own clock by default. You're driving your matrix chain from a metro running about 40 fps, and you're recording a file with 15 fps.

Every time jit.qt.record receives a new matrix, it adds it to the movie with no regard for the amount of time that has passed since the previous frame was added. You're adding frames at 40 fps. Then when you play it back, you're playing back at 15 fps, so it will look slower.

To solve this, set @realtime to 1, which will force jit.qt.record to capture matrices at the defined frame rate (and record frames from the last inputted matrix if there is no new input).