What is the difference between CPU transistors and generic ones?
MOSFET load drivers are much, much larger than the FETs used on a CPU chip: they have to be to deal with the voltage and current they’re designed to drive. As a consequence of their size they have large gate capacitance and so take longer to change their gate voltage from ‘on’ to ‘off’ state. Also, to achieve low Rds(on) appropriate for a driver, they need higher Vgs(on) than a CPU FET. This adds even more to the charge burden, and thus the switching time.

In contrast, CPU transistors are physically small, work at low voltage, and are driving relatively tiny on-chip loads. They have small gate capacitance and a low Vgs(on) so they can switch very quickly. They’re also sometimes allowed to have an extra-low gate threshold and even a bit of leakage, so the gate voltage swing needed to switch them is reduced even further.