It has for me, under Win 8.1 and five builds of Win 10 TP now I have a noticeable difference between when I have it installed and running and when I don't. Certain things, like a bunch of Windows updates, will turn on the blower no matter what, but normal operation I have far less fan frequency and noise with it than I do without. Noticeably so.
SpeedFan? No. But there is a noticeable audible difference. Everytime I take it off I end up putting it back on. There was another one - TPFanControl - and I used it on all my ThinkPads over the years. Think there's multiple profiles out there for that multiple machines, haven't checked to see if there are any for SP3s.
AFAIK there's no Fan Sensor (or it's not exposed) in the SP3 which is why there's not any display of fan speed and no control to manipulate the Fan. Maybe Speedfan is manipulating something else and there's a knock on effect but I don't think the ability to monitor or manipulate the fan is exposed by Microsoft, probably with good reason.