In the days before low stretch sheets and sail cloth, and in the days when most boat's windward performance was limited by their inefficient long keels as much as by thier sails, cutters with their comparatively small headsails were considered quite weatherly since weather performance was less diminished by the smaller amounts of stretch that occured with their proportionately smaller headsails. With modern low stretch sail cloth and modern low stretch
line, stretch has become far less of an issue, and so the interference between the forestaysail and the
jib becomes far more critical in affecting windward performance.
In other words, when you have two headsails filling the foretriangle there needs to be an adequate slot between the
jib and the mainsail and then a second adequate width slot between the forestaysail and the
jib. This makes a wider forestaysail sheeting angle and that typically greatly limits how close a cutter can point as compared to a sloop.
Jeff