Does virtual function really influence the performance?

[code_discuss]

I keep reading articles which say virtual function has overhead on performance, but I'd like to know how much is it? For example, the MFC framework, if all the functions inside are virtual, how much will MFC's performance decrease, for the current 1GHz/512M PC hardware ?:confused:

[Arman S]

Yes there is overhead on performance. But it is very important to understand the virtue/performace relation when using virtual functions. I mean, one should avoid using virtual functions in low level operations such as accessing each character in a sequence. But for not so heavy and/or intensive operations you can [and sometimes should] ignore performance issues. As for MFC, a good candidate area of using virtual functions is message handlers. But MFC refused virtual functions and used message maps. Really, so many classes with so many virtual functions would indeed decrease speed and increase memory usage.

-- ===== Arman