how to improve the throughput of linux network

[zhengchuanbo]

we use linux as our router. i just tested the performance of the router with smartbits, and i found that the throughput of 64byte frame is only 25%, about 35kpps. 
someone mentioned that the throughput of 64byte frame could reach 70kpps.so i wish i could improve the performance of our router,but i don't know how to do that.
i looked for some solution,and found some article mentioned the NAPI. it changed the driver to polling mode,so that the interrupt is no too much. but i could not find  drivers for our router.(eepro100 card). has the polling mode driver been used in linux?
i think there should be some other methods to improve the performance.but what is the most efficient one?
thanks for help. please cc.

chuanbo zheng