I’ve been cannibalising pieces of two vehicles into my armored car, and at some point during the process the game became laggy and prone to crashes. Doing stuff like installing a few pieces of armor, or even just eating a piece of food frequently causes a crash in this state, and if I try to sleep the time moves forward very slowly. As soon as I drive my vehicle a bit further away the lag and crashes disappear.
I was playing on 0.C-7987, and after the crashes began I tried running the save on the latest version I could find -8019. The lag and crashes seem to persist there, and as before they stop when I either drive my car away from the other two cars, or simply walk far enough away from all three of them.