The time needed to fit a single waiting-time series is approximately equal to ζ × N D × N p where ζ is a constant specific to the computer, N D is the number of data points and N p is the number of variable fitting parameters. The Jacobian 𝐉𝐉 requires 2N p unique calculations of the model 𝐌𝐌(𝐩𝐩) for the central finite-difference approximation, and hence, the bottle neck of the program is computing 𝐌𝐌(𝐩𝐩). We estimate ζ ≈ 1.3 × 10 -7 minute/point/parameter for CPU computing on the laptop described above. For spectra smaller than 10 6 points, ζ is roughly the same between CPU and GPU computing. For spectra larger than 2 × 10 6 points, GPU computing reduces ζ by a factor of two or greater.