>I think this->... would be something like function call.
Dereferencing a pointer isn't like a function call. And because this is done implicitly anyway, the two methods are probably identical in performance. I don't really have the inclination to go rooting through the standard to verify this, so I'll just say that even if they aren't identical, it really doesn't matter because the difference would be negligable.

On one of my compilers (MVC++ .NET) the code:
Code:
class C {
public:
  C();
private:
  int i;
};

C::C()
{
  i = 10;
  this->i = 10;
}

int main()
{
  C c;
}
results in the following relevant piece of assembly code using the /Fa switch:
Code:
; Line 10
	ldarg.0				; _this$
	ldc.i4.s	10		; i32 0xa
	stind.i4	
; Line 11
	ldarg.0				; _this$
	ldc.i4.s	10		; i32 0xa
	stind.i4