I did some testing and managed to determine that the formula used is

`Speed Multiplier = 2^(Simspeed/3)`

In other words, every +3 difference in simspeed is a doubling of the simulation tick rate. Here's a handy dandy table for those curious:

Simspeed | Time Factor* | *For positive sim speeds the time factor is times faster, for negative sim speeds it is times slower |
---|---|---|

0 | 1× | |

1 | 1.25× | |

2 | 1.59× | |

3 | 2× | |

4 | 2.52× | |

5 | 3.17× | |

6 | 4× | |

7 | 5× | |

8 | 6.35× | |

9 | 8× | |

10 | 10× |

Can't say this is the most useful information, but I found it interesting.