IGeometryCollection.AddGeometry - reusing Point reference

I am trying to create a large number (>10k) of convex hulls using ITopoOp.convexhull and each ConvexHull has more than 2000 points. I am using a Multipoint Geometry collection and adding 2000+ points using AddGeometry(). However, I have to create a new Point() every time I add a geometry to the geometriccollection. This is causing a major performance lag in the application. However, if I do not call new Point(), the resulting convexHull is incorrect as all the geometries in the collection have the same Point. Is there a way I can get around this or is there an alternate solution, to speed up the creation of convex hulls.

{

P = new ESRI.ArcGIS.Geometry.Point();
P.SpatialReference = sr;
P.PutCoords( inmemory_features[rs].x, inmemory_features[rs].y );
geomcoll.AddGeometry( P as IGeometry, ref missing, ref missing );
}