In Genetic Algorithms, the idea of elitism is that we keep our best solution from the generation in our population regardless of what happens throughout the iteration. However, elitism seems to be discussed as an optional thing; so what situations is using elitism actually a negative aspect of a genetic algorithm?
It increases the convergence speed of the GA, which is a double-edged sword. You want the algorithm to find good solutions quickly, but not so quickly that is has not been able to sample sufficiently large areas of the space that it's not just doing a very local search around the initial population.
Another option that can work well is to be elitist, but try to intelligently figure out when you've converged and should introduce some diversity.