diff --git a/WHATSNEW b/WHATSNEW
index b3935d3e6..3b2f3a84d 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -45,6 +45,12 @@ Fixed bugs:
    a temporary file.
    Bugzilla Report 49419.
 
+ * Ant would often scan directories even though there were known to
+   only hold excluded files when evaluating filesets.  This never
+   resulted in worng results but degraded performance of the scan
+   itself.
+   Bugzilla Report 49420.
+
 Other changes:
 --------------
 
diff --git a/src/main/org/apache/tools/ant/DirectoryScanner.java b/src/main/org/apache/tools/ant/DirectoryScanner.java
index ecd4e8726..7531954d4 100644
--- a/src/main/org/apache/tools/ant/DirectoryScanner.java
+++ b/src/main/org/apache/tools/ant/DirectoryScanner.java
@@ -1255,7 +1255,8 @@ public class DirectoryScanner
                 } else {
                     everythingIncluded = false;
                     dirsNotIncluded.addElement(name);
-                    if (fast && couldHoldIncluded(newPath)) {
+                    if (fast && couldHoldIncluded(newPath)
+                        && !contentsExcluded(newPath)) {
                         scandir(file, newPath, fast, children,
                                 directoryNamesFollowed);
                     }