Amazingly stupid that Sonar will autosave immediately after you cntrl/save.
Yes & no, autosave saves to it's own file so sometimes I'll use it like a temporary versioning if I'm off on a tangent with a project. I also regularly use Ctrl-S under normal circumstances which as pointed out I also have control over.
I noticed you also said saving takes a long time, do you find that all the time? I've recently had that on a project where saving takes several seconds (5 or 6+) where normally my projects save in no more than couple of seconds regardless of size. I think that must have been some sort of quirk with that one project, it's the only one that has ever taken that long although others have mentioned Audiosnap can cause saving to take a while if it's applied to tracks even if not actually using it.
I also find size of a project has little to do with save time, as far as I understand it the save is saving pointers and layouut etc rather than actual audio which is saved as it's written. Having said that I use lots of external gear rather than virtual instruments so that may make a difference.
If my saves where taking several seconds I wouldn't be using autosave either. AFAIK autosave has never saved for me while recording or playing back either regardless of settings.