Mage Cool time for magic missle slowed down what happened?

[baneswrath]

I have magic missile on lvl1 so I can spam it. The cool time is maxed out and I used to be able to cast like ever 1.5s or so. When I hit lvl49 I got magic burst and maxed out the cool time on it. I ran out to try it immediately because I was excited to have it and I noticed it had a lot slower casting time than magic missile even though the cool time stats where the same. I then used magic missile and was shocked to discover that it had slowed down to match magic burst. Instead of being able to cast it every 1.5s I can only cast it like every 3.5s now. I asked around and for some people it had slowed down to and for others nothing had changed. What in the world is going on lol anyone know?