Can I make the Arduino ignore serial print
If you insist on top performance, the best thing would be to use a macro for that:

#define Sprintln(a) (Serial.println(a))


Then instead of 

Serial.println(F("Hello world!"));


write 

Sprintln(F("Hello world!"));


etc. To deactivate the Serial printing, define the macro empty:

#define Sprintln(a) 


This will have the preprocessor remove all debugging code defined with Sprintln from your code.

(Of course, there's a huge number of variations on this theme.)