Probably an approach maybe that of increasing progressively the level of theory, so to reduce the number of cycles at the highest level. Therefore, you may try to start with a AM1 > PM3 > DFT (small BS) > DFT (medium BS) > DFT (large BS) > properties. You may also want to split the optimization in two steps, one with a loose optimization followed by a finest one. In each DFT step you may use the results from the previous level (guess=read, geom=allcheck). You may alternatively consider an ONIOM approach, depending on the nature of the molecule.
Consider carefully the required memory. You may want to use GaussMem for a reasoned evaluation of the RAM and compare to the amount of RAM available on your laptop.
A final consideration: install a Linux OS on your laptop for a better management of the (probably limited) available resources in terms of cores&RAM.
