Altera SGDMA & TSE

Hi..I am using NIOS II Small CPU at 125MHz frequency & ram size is 128MB. I have tried with -O2 optimization but didn't see any difference in performance. In the callback function first I am calling tse_mac_rcv() and then after checking for chain complete mask & status tse_mac_axRead() is called which inside calls do_async_transfer(). After that I am putting my logic for received packet. Is this the correct way to handle ISR callback? With this configuration my ISR callback is called max upto 250-300 times in a second and which indicates the maximum speed we can achieve to 250-300KBPS. Is there any other way we can handle these logic? I have not tried with multiple chain desciptor.