diff --git a/database/DBcellcopy.c b/database/DBcellcopy.c
index f8f147cf..e7d130d9 100644
--- a/database/DBcellcopy.c
+++ b/database/DBcellcopy.c
@@ -1209,6 +1209,10 @@ DBCellCopyAllCells(scx, xMask, targetUse, pArea)
     GeoTransRect(&scx->scx_trans, &scx->scx_area, &arg.caa_rect);
 
     (void) DBTreeSrCells(scx, xMask, dbCellCopyCellsFunc, (ClientData) &arg);
+
+    /* dbCellCopyCellsFunc() allows cells to be left with duplicate IDs */
+    /* so generate unique IDs as needed now.				*/
+    DBGenerateUniqueIds(targetUse->cu_def, FALSE);
 }
 
 /*
@@ -1306,17 +1310,12 @@ dbCellCopyCellsFunc(scx, arg)
 	return 2;
     }
 
-    /* When creating a new use, try to re-use the id from the old
-     * one.  Only create a new one if the old id can't be used.
-     */
+    /* When creating a new use, re-use the id from the old one.		*/
+    /* Do not attempt to run DBLinkCell() now and resolve unique IDs;	*/
+    /* just create duplicate IDs and regenerate unique ones at the end.	*/
 
     newUse = DBCellNewUse(def, (char *) use->cu_id);
-    if (!DBLinkCell(newUse, arg->caa_targetUse->cu_def))
-    {
-	freeMagic((char *) newUse->cu_id);
-	newUse->cu_id = NULL;
-	(void) DBLinkCell(newUse, arg->caa_targetUse->cu_def);
-    }
+
     newUse->cu_expandMask = use->cu_expandMask;
     newUse->cu_flags = use->cu_flags;
 
diff --git a/database/DBcellname.c b/database/DBcellname.c
index 72d4b8b5..944c6a60 100644
--- a/database/DBcellname.c
+++ b/database/DBcellname.c
@@ -2098,6 +2098,14 @@ DBCellSrDefs(pattern, func, cdata)
  * This operation is not recorded on the undo list, as it always accompanies
  * the creation of a new cell use.
  *
+ *		    *** ANOTHER WARNING ***
+ *
+ * Do NOT pass a NULL cu_id to this routine when doing bulk cell copies,
+ * because an entire hash table of entries for the parent def will be created
+ * and searched for every cell being linked, making the routine run-time
+ * exponential with the number of links.  It is better to run
+ * DBGenerateUniqueIDs() instead.
+ *
  * Results:
  *	TRUE if the CellUse is unique within the parent CellDef, FALSE
  *	if there would be a name conflict.  If the cu_id of the CellUse
@@ -2363,8 +2371,9 @@ dbFindNamesFunc(use, parentDef)
 	he = HashFind(&dbUniqueNameTable, use->cu_id);
 	if (HashGetValue(he))
 	{
-	    TxError("Duplicate instance-id for cell %s (%s) will be renamed\n",
-			use->cu_def->cd_name, use->cu_id);
+    	    if (dbWarnUniqueIds)
+		TxError("Duplicate instance-id for cell %s (%s) will be renamed\n",
+				use->cu_def->cd_name, use->cu_id);
 	    DBUnLinkCell(use, parentDef);
 	    freeMagic(use->cu_id);
 	    use->cu_id = (char *) NULL;