You do realise that drawing the characters to the screen is an order of magnitude (at least) slower than grabbing some heap memory, doing a string conversion an

You do realise that drawing the characters to the screen is an order of magnitude (at least) slower than grabbing some heap memory, doing a string conversion and freeing the memory, right? You don't even need to allocate memory - you can have a constant small thread-local buffer of, say, 1kb that you reuse for these conversions.