Trends in the signed errors are particularly interesting, with all but four methods (ADC(3), ADC(2.5), tPBE, and tPBE0) overestimating excitations; this implies biased relative overstabilization of the ground state for most of the methods. One can clearly see how tPBE0 benefits from balancing the treatment of exchange and correlation, with SA-CASSCF overestimating excitations by 0.18 eV and tPBE underestimating by 0.08 eV such that tPBE0 has nearly zero mean signed error. We note that the same good balance seems to occur in ADC(2.5), which averages ADC(3) and ADC(2). Figure shows the mean absolute error of different methods on excitations classified as double excitations for all methods with any calculated double excitations in the QUESTDB database; our automated approach was able to converge results within the 1.1 eV SA-CASSCF error threshold for 16/23 (70%) of the double excitations that have TBEs available, which is only slightly lower than the overall un-dropped-out fraction of 436/542 (80%) in the Aug (12,12) calculations. In keeping with the usual recommendation to use multireference methods for this class of excitation, we find that multireference methods are the only methods that perform consistently well on double excitations. Figure shows the errors classified by excitation type. In line with the Sarkar study, we find that NEVPT2 is more accurate for triplet excitations than singlet excitations, and tPBE and tPBE0 follow this same trend. The figure shows that, with the exception of Rydberg states, tPBE0 has better performance than tPBE for every excitation category, and therefore we recommend the use of tPBE0 rather then tPBE for calculating excitation energies of valence excitations. We also recommend tPBE0 for calculating a spectrum containing both valence and Rydberg excitations since the performance of the two methods is very similar (on average) for Rydberg states. Figure shows the average time consumed by the calculation of the NEVPT2 perturbative correction at different active space/basis set sizes and compares these timings to those for the calculation of the tPBE on-top energy by the methodology in section 2. We find that at the normal grid size (grids_level = 3 in PySCF), tPBE is on average 114× less expensive than NEVPT2 for the large max (12,12) active spaces. This is because -as is well known -the cost of NEVPT2 scales very poorly with the size of the active space, while the cost of tPBE0 remains independent of that. Furthermore, the memory required for NEVPT2 also increases with active space size. It is around the max (12,12) active space size that the compute time for the perturbative correction begins to exceed the compute time of the underlying SA-CASSCF step, while the compute time of tPBE remains low. For smaller active spaces such as max (8,8), the cost of NEVPT2 is comparable to that of tPBE and tPBE0.