That logic is awesome 
C++ compiling is slow. Blueprint compiling less so. So put C++ into blueprint nodes then its faster. 
That isn’t going to work.
Try to imagine what blueprint nodes are. They are mappings to a lot of code that has been written in C++. That is already developed and compiled into the editor, and the game, so that’s part of why blueprints are ‘faster’ in this case. Parse and generate binary code from C++ is not easy at all, that’s part of why compiling C++ is so slow (especially on Windows, where process startup is so damned slow).
Don’t be offended, I don’t mean to offend. Of course if you meant something totally different like convertig string Im sorry for the misunderstanding.