Virtual Functions and Performance C++

Question

Before you cringe at the duplicate title, the other question wasn\'t suited to what I ask here (IMO). So.

I am really wanting to use virtual functions in my applicat

Answer 1

There is a performance impact to calling a virtual function, because it does slightly more than calling a regular function. However, the impact is likely to be completely negligible in a real-world application -- even less so than appear in even the most finely crafted benchmarks.

In a real world application, the alternative to a virtual function is usually going to involve you hand-writing some similar system anyhow, because the behavior of calling a virtual function and calling a non-virtual function differs -- the former changes based on the runtime type of the invoking object. Your benchmark, even disregarding whatever flaws it has, doesn't measure equivalent behavior, only equivalent-ish syntax. If you were to institute a coding policy banning virtual functions you'd either have to write some potentially very roundabout or confusing code (which might be slower) or re-implement a similar kind of runtime dispatch system that the compiler is using to implement virtual function behavior (which is certainly going to be no faster than what the compiler does, in most cases).