Performance issues related to the use of Threads and Events???

In my MFC dialog based application there are 2 parent threads and inside the parent thread there are 3 child threads and these are synchronized using CEvent-- SetEvent() and ResetEvent().
The input file is readed as blocks of 16 char.Shared buffer is used for storing the blocks.

child thread1 -- used for read a block(16 char) from file1
child thread2 -- used to perform some task on block readed by thread1
chikd thread3 -- used to write the modified block to file2

These three child thread are in while loop until block > 0.

The child thread1 sets event for child thread2 and child thread2 sets event for child thread3.

The run time performance of the application is very poor for the large files. How can I increase the performance as the application runs very slow?

Tags: C++, C, MFC, Threads