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.