Network Interface Tuning

Use a well supported card. 
ie, eepro100's, tulips, 3com, acenic and sysconect gigabit cards

Full duplex mode is often a big win, especially in benchmarks
options eepro100 full_duplex=1
similar syntax for most "becker derived" modules

Some case, half duplex sometimes offers much better one way performance. 
Best to test and see