iMovie very slow to save minor changes

hi

I'm new to iMovie so I may be missing something...

I made a couple of movies and saved them ok, then I decided to just change the name of one movie and I noticed that a progress indicator at the top right hand corner of the iMovie window (circle) was spinning extremely slow and it took about 10 minutes to complete, and all I did was change the name of the file.

The first time I made a file name change, I hadn't noticed the progress indicator and closed iMovie and it told me that there was a process happening.

Is this normal for iMovie?

I have the latest Mac Mini with 8 gb of RAM

thanks

nick