The spinnaker will collapse or behave strangely. If you are ahead, and the boat behind blankets you, you should immediately head up or jibe. If you are sailing in more wind, don't jibe but merely head up. There is a narrow band beyond which there is diminishing return. A boat may move faster but will move farther from the mark or it will move slower but move closer to the mark.
Most boats make their best speed when headed closer to the mark.
A sample scenario would be to round the mark and sail a compass course direct to the mark. Assume it is 5 knots. Come up 20 degrees and note the boat speed. The solution is to sail low and slow but more directly to the mark. If there was a favored side going upwind then sail to that side when going down wind.