You can save some time by ending each simulation immediately if it has fewer cells than the starting number and is within the same 10×10 bounding box, as it duplicates another simulation.
You can also cut down the simulations by 1/4 (although it's still more than 2^49) by saying that the four center cells have three possibilities: all on, all off, or two on and two off; the last of the three categories has two configurations for each but can be reduced to one because it's the same soup flipped/rotated.
What we are looking for:
- Unknown oscillators with period 4 or greater (this is the main reason to do this)
- Unknown spaceships (much more likely in mirror symmetry than rotational symmetry)
- Quadratic growth
- 50000+ generations