I have an old project that got very large (300+Mb !)
This resulted in frequent crashes and very slow operation.
At the time I trimmed the project down but it was still in excess of 250 Mb, but I was able to finish.
(I should have expected a much smaller project, but it was early in the morning!)
I have just been required to edit another couple of sequences from the same material.
I did a “save as” and deleted all but the master clips within folders that I needed.
The project size was still 239 Mb. I closed FCP and restarted but this value remained.
(All 600Mb of my original rushes are on my media drive still.)
I had deleted all of the old sequences multi-clips etc. I deleted the few old render files.
I then made a new project and tried to drag the master clip folders I needed ( a small subset of the original) between projects.
My MBP crashed each time. (17in with 4Gb memory)
I then in another new project this time copy and pasted the required clips with success.
The project now contains the same clips as previously, but is now only 2.6 Mb.
Can any one explain that? (Perhaps it is the undo buffer? How do you clear that?)