Dealy in Data reception through serial communication in MATLAB

Iam developing a MATLAB Graphical User Interface in Matlab R2007a Version using serial(RS232)commuication.

During serial communication, sending of data is working properly but their is a too much delay in receiving the data from our microcontroller (AT90CAN128). How can i reduce this delay?

Note: Iam using fwrite to send the data. Ex: fwrite(obj1,txdata);

And, fread to receive the data.Ex: [rx_data, count] = fread(obj1);

Please suggest me the solution.

Thank You...