Improve memory management. Several techniques are used. First, we use arrays in shared memory when computing the SEDs (this should also be done for the analysis later). This avoids using temporary objects that have to be sent back into a list from pool.starmap. Second, we do not save the sed.info data until the best sed has been computed. Only then we recompute the SED to get the info. Third, the list of changed parameters for cache cleaning was too big. It contained the key and the value of the changed parameter to identify models to be discarded. Now we simply return an array of integers giving the index of the module to be discarded. Much simpler, much smaller. There are also some small improvements here and there that I probably forget. The main culprit now is by far the list of parameters. It gets horribly big. 3.5 GB for 30M models. Anyway, now pcigale runs with 30M models.