altera Board DE2

hi, I have a aletra DE2 baord and i use tutorial DE2.net. it fonctionne correctly but I would wish to increase the speed transmission of the data. speed to measure is of 170kb/s by default. if one reduit the delay one can increase 270kb/s. ( program DM9000A.h STD_DELAY by default 20us) how to increase the speed of transmision of the DM900A?