We have examined the use of TDKS or "real-time" TDDFT simulations for core-level spectroscopy at various elemental K-and L-edges. At first glance, the TDKS approach seems attractive for this application. It allows all of the elemental x-ray edges to be computed at once, in a single broadband calculation, up to an energy scale that is varies inversely with the time step used to integrate the equations of motion. In practice, however, TDKS spectra are contaminated with transitions to the continuum, to the point that they are frequently uninterpretable. A post-processing filter restores interpretability by decomposing the full TDKS spectrum into components defined by subsets of the MOs, and meaningful NEXAFS spectra can be recovered. However, the cost remains an order of magnitude larger than conventional LR-TDDFT within a CVS-style active-space approximation that uses only the core MOs of interest. This is true despite the use of Padé approximants to process the TDKS data, which reduces the simulation time required to resolve the nearedge features to ≈ 2 fs.