Since there is the possibility to make time go faster in singleplayer, why not also add an option to slow it down? At this time you can increase the speed of time to 4x normal. However, some people (like me) also want to be able to slow it down in order to "capture the moment" so to say when either showcasing a new mod in the making, or studying the various events that take place during a reaction, like when an artillery shell is about to hit the ground or a vehicle is about to explode. Personally, since you can increase the speed of time to 4x the normal, I believe players should also be able to slow it down to 0.25 of the normal rate, with 0.50 being the link in-between the two.