We have a system, written by C++. When it starts running, it will start an addon program. The addon is a COM EXE (outer process server). Customers can call the addon, get the system pointer, developing new features for the system. The performance is good under windows XP, but it is slower 7~8 times after we install our system on the Windows 7. I add amount of data into system, record the time at different parts. Finally, I found that the interprocess calling is very very slow. I don't know why? Could anybody help me? I was persecuted by it for a long period.