Optimizing the calculated fields by simplifying their formulas or pre-calculating values where possible The most effective action to resolve delays caused by complex calculated fields in a Tableau dashboard is to optimize these fields. This can be achieved by simplifying the formulas used in the calculations or pre-calculating values in the data source, if possible. This approach directly addresses the root cause of the delays without the need for extensive changes to the server or dashboard. Option A is incorrect because while increasing hardware specifications might improve performance, it does not address the inherent inefficiency of the complex calculations. Op-tion C is incorrect as limiting user access does not solve the underlying issue with the calculated fields. Option D is incorrect because rebuilding the entire dashboard is an excessive measure and may not be necessary if the calculated fields can be optimized.