FWIW, you don't have to be faster than the bear.

Strictly speaking, "CPU bound" is not an adjective that can be used to describe tasks. It's one that describes a particular program solving a particular task under a particular configuration. I've done no analysis on this myself, but I would be more than willing to believe that a CPU-bound job might be only a CPython-to-MyPy's worth of speedup away from instead being memory- or disk-bound.

It can be hard to tell the difference, too, since being stalled out while waiting on the memory controller shows up as CPU activity in htop.