--- a/eric6/Plugins/VcsPlugins/vcsPySvn/SvnDiffDialog.py	Sun Apr 11 16:53:48 2021 +0200
+++ b/eric6/Plugins/VcsPlugins/vcsPySvn/SvnDiffDialog.py	Sun Apr 11 18:45:10 2021 +0200
@@ -261,10 +261,12 @@
                             
                             self.__appendText(
                                 "{0}{1}".format(line, os.linesep))
-                            if counter % 30 == 0:
+                            if (
+                                counter % 30 == 0 and
+                                self._clientCancelCallback()
+                            ):
                                 # check for cancel every 30 lines
-                                if self._clientCancelCallback():
-                                    break
+                                break
                         if self._clientCancelCallback():
                             break
             except pysvn.ClientError as e: