Hi Leon and welcome to the MSZ Forum.
Your problem should be easy to fix.
Stop rendering to .avi - this is a un-compressed file format and should never be used for final delivery of a project.
Video for Windows .avi can be used as an intermediate format during the production of a project, but in reality no one really does. There are far better options for this.
The first thing you need to do is delete all those massive files off your Hard Drive.
I would also suggest to open up the Movie Studio Temporary Files & Settings Cache and make sure you don't have any massive files hiding in there as well.
Open a File Explorer page in Windows and go to this address:
C:\Users\UserName\AppData\Local\Sony\Movie Studio Platinum\12.0\
Please note the UserName will be unique to your computer and say something different.
Once inside, you can sort via File Size and check if anything HUGE is in here - anything over a 1 Megabyte needs to go. The biggest files should only be up to about 500kB in here.
You should be rendering to Mainconcept AVC/AAC .mp4 for most projects.
I have a video showing how to do this here:
www.moviestudiozen.com/free-tutorials/sony-movie-studio-platinum/441-how-to-render-1080p-video-movie-studio-platinum-12
Regards
Derek
ℹ️ Remember to turn everything off at least once a week, including your brain, then sit somewhere quiet and just chill out.
Unplugging is the best way to find solutions to your problems. If you would like to share some love, post a customer testimonial or make a donation.
Offline Topic Author 
