my horse was SUPER hot when i first got her and would rocket over the jumps so fast you couldn't even tell they were there, lol. I would suggest finding a knowledgeable jumping coach who know how to start horses jumping to help you set up obstacles to help the rushing to the fence. Bounces and lines as well as grid work all help. I would also work in many small circles. Whenever your horse decides to speed up make small circles to slow her down and don't allow her to leave the circle until she's relaxed. This will take a lot of patience on your part, but she'll get it soon enough. In the beginning my mare took maybe 10 turns before even hinting at settling down, now (2 months later) she calms down in one. Maybe practice using half-halts to slow down your horse too. One of the most important things about jumping is pace control, and please do not attempt full courses until you have this under control. The main thing is to always stick with whatever you decide to do and not allow any leniency. Remember to be patient, it might take a while, but the results will hopefully be good =) Good Luck, and hope this helps!