Overclocking the Pi's CPU _does_ increase the speed of some operations, for sure. For example, in my network tests, I can get 1.9 Gbps on a 2.5G adapter with MTU 1500 at 1.5 GHz (default Pi 4 clock), or 2.2 Gbps at 2.0 GHz.

Using MTU 9000 lets me get over 2.3G on that adapter.