#### Describe the bug The core's Ethernet Server speed is normal for core v2.6.1- For `core v2.7.2 to v3.0.1`, the Ethernet Server speed is **extremely slow and almost unusable**. For example, try from complex example [**AdvancedWebServer**](https://github.com/khoih-prog/EthernetWebServer/tree/master/examples/AdvancedWebServer) to the simplest one [**WebServer**](https://github.com/arduino/ArduinoCore-mbed/tree/master/libraries/Ethernet/examples/WebServer) #### MRE Using the following core's Ethernet library example [**WebServer**](https://github.com/arduino/ArduinoCore-mbed/tree/master/libraries/Ethernet/examples/WebServer) with - Arduino IDE v1.8.19 - mbed_portenta `core v2.6.1` or `core v2.7.2 to v3.0.1` - Portenta_H7_M7 - Either static IP or DHCP #### Related issue [**[Portenta_H7] Ethernet not working in core v3.0.0** #436](https://github.com/arduino/ArduinoCore-mbed/issues/436)