Quote:
i simplify the code by applying object oriented but large file processing time not decrease
Simplified code is a prerequisite for code readibility and reliability, not for speed performance.
In order to speed up the code you should probably go in the opposite direction, that is go more low level (e.g. consider the interaction with the underlying OS in more detail, prefer raw access to resources intead of powerful abstractions and so on) and focus your
C++
code on speed optimization.
I cannot help you more without seeing the actual code.