If, as a progammer, I see something like this render taking 10 seconds, I will shake my head in confusion and think "what the hell is taking up all this time".

If, as a progammer, I see something like this render taking 10 seconds, I will shake my head in confusion and think "what the hell is taking up all this time". Stuff like loading the same font a hundred times, allocating memory for all the same symbols - identifying and getting rid of that is not premature optimization, its plain fixing the code. Of course you might have done all of that - no way to know unless you tell us more about the actual pipeline.