Optimise slow functions

[jbjjbjjbj]

Running 10000 simulations shows that the following functions are relatively slow.

• [ ] gmsk.modulate
• [ ] dect_4bit_crc

[vdot0x23]

With what purpose are you running 10 000 simulations?

Can you be more specific than "simulation", it is unclear what constitutes a simulation (e.g. refer to a file in examples/)?