This topic seems like it is posted every few hours. Do you have any clips that have the Warp Stabilizer on it?
I think I found an answer on another thread.
There's a known bug having to do with preview files & using Save As frequently - it'll double the number of preview file references incorrectly on each iteration. This will be fixed in the next update.
This is such a professional stuffup I can barely bring myself to write about it. How this got through QA mystifies me. And no I haven't used Warp Stabilizer on any CS6 project. At least I know I'm not the only one.
After reverting to an earlier project save, we lost a whole day of work. We have been monitoring the file size hourly and after seven hours editing the project jumped from an 82mb size to 1.5gb in a single save. Now it won't even reload. When we get through this project we are pulling all our CS6 Mac stations offline until this is resolved. I'm sorry guys but this really is hopeless. And no word of even an ETA on when this bug will be fixed.
Please try loading the project with the newly released 6.0.1 update. Let me know if it improves the project size - if it doesn't save back down to a reasonable size, PM me - I'd like to get a look at the new .prproj file to examine where the remaining bloat is coming from.