Not all Realtek NICs are fine at this point in time. For some models of Realtek NIcs the Linux driver has to memcpy() data for every single packet in order to

Not all Realtek NICs are fine at this point in time. For some models of Realtek NIcs the Linux driver has to memcpy() data for every single packet in order to work around a hardware bug. It's entirely possible that the Linux driver has that kind of workaround enabled for newer hardware that doesn't need it anymore, but getting that kind of driver change merged tends to be a bit of an uphill battle without having the hardware manufacturer actively involved in maintenance of the mainline open source driver.