All calculations so far have been performed in serial operation without leveraging the parallel implementation of CrystalEstimator. To test the effectiveness of the parallel implementation, one Sobol' point optimisation is run for each of the seven test problems using different core sizes (N c ) across a single node. Code speedup relative to serial operation is then analysed based on the number of workers (N c -1) used to perform the lattice minimisations and residual calculations. The speedup achieved for each test problem is plotted in Figure . Again, all calculations are performed using Intel Xeon 2.50 GHz CPUs.