@Vincent-TP
It would be important to achieve, estimate, and prevent future network problems.
Manage simultaneous connections (important in networks with many users or IoT devices);
Avoid crashes during traffic spikes or many connected clients;
Run advanced functions such as VPNs, firewalls, QoS, and detailed logs.
A single-core, low-frequency CPU can crash when applying complex firewall or QoS rules.
If you enable VPNs with encryption, the more powerful the CPU, the smaller the speed drop (encryption is processor-intensive).
In routers with NAT for many devices, a slow CPU can limit the actual throughput—you might have a 300 Mb/s link, but only reach 150 Mb/s because the CPU can't handle it all.