More precisely, I am wondering if there is any kind of data on how long it takes between moving the sidestick and observing a reaction on the ailerons or elevator. I know that the physical control surfaces take time to move and, thus, I am only wondering about the actual latency added by the fly-by-wire (FBW) system.
My naive assumption is that the A320 runs a fixed control loop with precise timings. So, every $n$ milliseconds it samples the sidestick, calculates the necessary control surface deflections and then sends that via some bus which runs at $m$ Hertz. So, on average there is an expected delay of $x$ milliseconds between input and the control surfaces starting to respond to the input.
Also, is the delay noticeable by pilots?