I suppose my point is that for applications where performance is a significant issue at all, there may be no useful interpretation of "premature optimisation".

I suppose my point is that for applications where performance is a significant issue at all, there may be no useful interpretation of "premature optimisation". You have to design with at least the ability to code efficiently from the start, without relying on abstractions that hide performance traps. Otherwise you can back yourself into a corner where the only way out is to redesign or even entirely rewrite large parts of your code, and I think it would be generous to consider that sort of change a mere optimisation.