If you do concatenation a lot, it's better (for performance, of course) if you make it a template (so Nim will just replace a + b with a & b): template `+`(a

If you do concatenation a lot, it's better (for performance, of course) if you make it a template (so Nim will just replace a + b with a & b): template `+`(a, b: string): string = a & b But probably C compiler is smart enough to inline your proc :)