Issue with Motion 3

[xx.terror.storm]

I am trying to make a clip a few seconds in length run in slow motion in FCP, and quite frankly, the results are horrible. I've heard that Motion is the way forward to get results, so I have sent said clip to Motion. But here is the problem...

I have about 50 odd gb of hard drive space. But as soon as I select Optical Flow for my clip it says I don't have enough hard drive space, and on further inspection it turns out I only have about 200 or so of mb space left! What is going on?

I tried to overlook this obscurity and deleted some stuff to free up for space (about 5gb). This allows me to perform an optical flow. However, it says it will take about 28 hours to do. Which is just ridiculous! Obviously there are a couple of serious issues here. Is anyone able to shed some light on any of them? Thankyou.

 

[xx.terror.storm]

Does anyone here use Motion 3? I seriously need some help! I forgot to mention the source file is coming from my external hard drive. Don't know if that would make a difference.