This is my opinion, but I also found that saving often seemed to noticeably increase performance. It seems to me, in whatever iteration of The Sims, doing so prevents some issues and eases lag (if there is any lag). There's no reason not to save often, just in case, even though after the 64 bit patch TS4 seems uncrashable (except for mod issues). Glitches or other forces might still muck it up.
Save early, save often - no matter what it is. It usually takes some catastrophe to drill it into us. I think that's why you got THIS mad about it; 6 hours play is so much to lose.
Beyond that, this is unfortunate to see, as that feature seems awesome and easily the best aspect of this stuff pack, by far. :/
