imovie 10.0.2 crashing/Not Responding/Huge drain on Mac resouces

Whats happened to iMovie? Ive updated to 10.0.2 and the software is now unusable. Very slow to load (if at all), none responsive then crashes. Its also slowing down my Mac making other apps slow. Useless!

How can I fix this?

I am not computer literate, so I would be grateful for any help with detailed instructions. Many thanks!

Im using a Mac, Mavericks 10.9.1 and iMovie 10.0.2