Fig. 2: Computational performance of the ultrafast algorithm.

Benchmark of different approaches/implementations for synthesizing time-resolved CRS spectra. ref refers to the reference approach based on Eq. 3, implemented as Python (-py) and C++ code (-cpp); ufa refers to the ultrafast approximation based on Eq. 7, also implemented as both Python (-py) and C++ (-cpp) codes. The fully optimized implementation (ufa-cpp) includes multithreading and full SIMD vectorization, which improves computation time by a factor of 1 M compared to the conventional approach (ref-py) for a large number of spectral lines. The performance in the 10⁷–10⁸ lines range is evaluated by synthetically expanding the number of lines in the MeCaSDa database (see Methods).