Index: epan/dissectors/packet-ftp.c
===================================================================
--- epan/dissectors/packet-ftp.c	(revision 43923)
+++ epan/dissectors/packet-ftp.c	(working copy)
@@ -634,21 +634,31 @@
         tvb_reported_length(tvb));
 
     if (tree) {
+        gboolean is_text = TRUE;
+        gint  check_chars, i;
         data_length = tvb_length(tvb);
 
         ti = proto_tree_add_item(tree, proto_ftp_data, tvb, 0, -1,
             ENC_NA);
         ftp_data_tree = proto_item_add_subtree(ti, ett_ftp_data);
 
-        /*
-         * tvb_format_text() is very slow for long (binary...) lines, so limit to
-         * size that will actually be displayed.
-         *
-         * Not clear if its really worth doing this for binary data, as bytes are not
-         * even shown as hex!
-         */
-        proto_tree_add_text(ftp_data_tree, tvb, 0, data_length,
-            "FTP Data: %s", tvb_format_text(tvb, 0, MIN(data_length, ITEM_LABEL_LENGTH)));
+        /* Check the first few chars to see whether it looks like a text file or not */
+        check_chars = MIN(10, data_length);
+        for (i=0; i < check_chars; i++) {
+            if (!isprint(tvb_get_guint8(tvb, i))) {
+                is_text = FALSE;
+                break;
+            }
+        }
+                
+        if (is_text) {
+            /* Show as string, but don't format more text than will be displayed */
+            proto_item_append_text(ti, " (%s)", tvb_format_text(tvb, 0, MIN(data_length, ITEM_LABEL_LENGTH)));
+        }
+        else {
+            /* Assume binary, just show the number of bytes */
+            proto_item_append_text(ti, " (%u bytes data)", data_length);
+        }
     }
 }