Hi Massimo,
I am using WARP stabilizer, and have used it in the past, and there was never an issue. It was definitely not the use of the WARP stabilizer that caused the project file to swell from 50 MB to 295 MB in one session.
The only significant thing that I did differently in that session was to place one clip on the “Soft Light” blending mode.
It seems to me that this is simply a problem in Adobe Premiere (I am using CS6 on a PC). I hope that the Adobe company takes heed and makes a solution available.
Thanks.
Amar