Pretty simple - the act of saving a song file, whether done manually by pressing Ctrl + S or by autosave every few minutes, takes much longer in Studio One version 5 compared to 4. I've tested with identical Song files, although it doesn't take an idiot to notice that I've never had a problem saving large projects nearly instantaneously in V4, and now they cause the program to freeze up for several seconds. This is especially frustrating when done by autosave as it interrupts whatever I was doing with a dialog box (it's also visually different than in v4 - 50% opacity, no title bar) which makes the entire program unusable until it goes away. A small detail, but very frustrating. Combine that with all the stability and CPU efficiency problems with V5 and the lack of any new features in the artist version makes this a very disappointing upgrade indeed.