Linux: How is the input latency of a Wacom tablet distributed among the various software- and hardware components?

Say I have the following setup: - Linux Kernel - input-wacom kernel driver - xf86-input-wacom X11 driver - Wacom tablet How is input latency distributed among these various components? Are there any bottlenecks? If one wanted to make software patches to reduce latency (even by a couple of milliseconds), which parts of the "pipeline" should one look at first?