diff --git a/include/lsst/afw/detection/FootprintSet.h b/include/lsst/afw/detection/FootprintSet.h
index dbbb615019..5635be0d44 100644
--- a/include/lsst/afw/detection/FootprintSet.h
+++ b/include/lsst/afw/detection/FootprintSet.h
@@ -224,7 +224,7 @@ class FootprintSet {
      * @param rhs the Footprints to merge
      * @param tGrow No. of pixels to grow this Footprints
      * @param rGrow No. of pixels to grow rhs Footprints
-     * @param isotropic Use (expensive) isotropic grow
+     * @param isotropic Grow isotropically (as opposed to a Manhattan metric)
      */
     void merge(FootprintSet const& rhs, int tGrow = 0, int rGrow = 0, bool isotropic = true);
 
diff --git a/src/detection/FootprintSet.cc b/src/detection/FootprintSet.cc
index 43cee9fde1..db598cd9a8 100644
--- a/src/detection/FootprintSet.cc
+++ b/src/detection/FootprintSet.cc
@@ -222,7 +222,6 @@ FootprintSet mergeFootprintSets(FootprintSet const &lhs,      // the FootprintSe
     // The isXXX routines return <isset, value>
     bool const circular = ctrl.isCircular().first && ctrl.isCircular().second;
     bool const isotropic = ctrl.isIsotropic().second;  // isotropic grow as opposed to a Manhattan metric
-                                                       // n.b. Isotropic grows are significantly slower
     bool const left = ctrl.isLeft().first && ctrl.isLeft().second;
     bool const right = ctrl.isRight().first && ctrl.isRight().second;
     bool const up = ctrl.isUp().first && ctrl.isUp().second;