Runaway 'Rendered files' folder now at 130gb! Solutions?

[Ru_C]

Hi all, I've got a 96k Project where the 'Audio' folder sits at around 40GB, but the 'Rendered Files' folder has ballooned to 130gb.

I've done the usual process of selecting all unused files in the Clips Browser, & ALT 'hard-deleting' them to remove any unused takes etc, as I've been doing for years now with earlier versions of PT.

Doing this gets the 'Audio' folder down to 30GB, but the 'Rendered Files' folder stays unchanged.

If however, I do a 'Save a copy in' & make sure all audio & hidden playlists are included, the copied project has an identical 'Audio' folder' size of 30GB as expected, but the 'Rendered Files' folder has now shrunk to a sensible 15gb.

So am I doing something wrong when I freeze & unfreeze tracks & folders (as I do a lot now), or is Pro Tools Ultimate at fault here ?

What is the best practice to avoid this situation reoccurring?