re-use of impulse response models of n-ports

Hi

My intention is to speed up my simulations (envlp) by re-use of impulse response models of the n-ports and I was hoping to get some help on how to preceed!

During the envlp sweeps, I see that the first simulation takes about 40 minutes to for spectre to complete (including calculattion/create impulse response bin files) while the following steps in the sweep take no more than couple of minutes (useing the models). But with no changes/updates of the schematic/N-ports/netlist, on the next sweep once again the first simulation takes about 40 minutes and all the bin files are re-generated on the first run.

Is there a way to force specter to re-use the same bin files it created during the very first impulse response calculation for the coming sweeps?

Thanks!