find_first_of: A performance pitfall among the STL algorithms

I live in Greece with my wife and our two daughters. I am a professional software developer since 1999, using mostly C/C++ in my work.
 
My main expertise are: C/C++, STL, software optimization, generic programming and debugging. I am also very experienced in client–server programming, communications, concurrent programming, software security and cryptography. Finally, in my early professional years, I have worked a lot on cross-platform programming (Mac+Win).
 
I am familiar with the MFC, wxWidgets and Cplat GUI frameworks and the Python, Java, Pascal, Fortran, Prolog and Rexx programming languages.