You're not deleting any RealTracks. The 'button' deletes files that are not needed with the new stretching engine. The 'old' RealTracks had several files that were used to transpose the instrument into other keys. These are the +/- files that is referred to. There is an option in the RT settings that enables the use of these +/- files. If it is not checked, the new engine is being used. If your computer is slow, the option to use the +/- files is there.

My understanding is that using the new engine is a bit slower than the +/- route.

If you look in a RT folder, you'll see the +/- files. As stated, make sure you have a copy of your RTs before deleting the +/- files.

Here is a post I made yesterday with more info. http://www.pgmusic.com/forums/showflat.p...true#Post297218