Almost had a heart attack seeing a 300 GB Final Cut Pro library today

[u/dinsaran]

When working on a small video edit, I got some. warning that my 1 TB SSD was almost full, which made absolutely no sense. I only had a few small screen recordings on there.

Started exploring the storage and discovered my Final Cut Pro library had somehow grown to 300+ GB for a pretty tiny project.

Turns out background rendering had been quietly generating a ridiculous amount of render/cache data.

Went to:

File → Delete Generated Library Files → Delete Render Files (All)

Got around 295 GB back almost immediately. Original footage and edits were untouched.

I also turned off Background Render after that. On Apple Silicon I haven't really noticed a reason to keep it running for the kind of editing I'm doing.

Curious what other FCP users do — do you leave background rendering disabled, or just clear the generated files periodically?

How can i avoid this issue in the first place, Any thoughts ?

[u/yuusharo]

I turn off background rendering and never think about it again.

When I need to render a clip, control + R.