I should have said heuristics, rather than optimizations. For example, if the point of the next insertion is usually "very close" to the previous insertion, you can make a significant improvement in the performance (e.g. O(n) vs O(n log n)). At any rate, choosing a O(n) algorithm up front instead of a O(n log n) algorithm shouldn't be dismissed as "premature". It could be, in fact, a well-timed optimization of your development process. :-)