Dependency code doesn't understand implicit intersection
COLA is defined as the whole A column. Run gnumeric on this file with GNM_DEBUG=deps and click the info button. Note, that C{1,2,3,4,5} depend on the entire A column instead of the single cell they actually use.
The dependency simple sees A:A (via the name, probably not important) and goes to town. There even is a comment to this effect:
/* TODO: pass in eval flags so that we can use implicit
* intersectionThis is highly wasteful.