Improve performance wen loading file previews.

borgmatic/actions/browse/file_preview.py

@@ -75,19 +75,14 @@ class File_preview(textual.widgets.RichLog):
         )
 
     def on_file_preview_loaded(self, file_contents):
-        import time
-
-        logger.debug(('on_file_preview_loaded', time.time()))
         self.loading_timer.stop()
         self.clear()
 
         if file_contents is None:
             self.write('Cannot display a preview for this file')
         else:
-            logger.debug(('before write', time.time()))
+            # Only pass the file path and not its contents to guess_lexer(). Passing the contents is
+            # more accurate, but also much slower.
             self.write(
-                rich.syntax.Syntax(
-                    file_contents, rich.syntax.Syntax.guess_lexer(self.file_path, file_contents)
-                )
+                rich.syntax.Syntax(file_contents, rich.syntax.Syntax.guess_lexer(self.file_path))
             )
-            logger.debug(('after write', time.time()))

borgmatic/actions/browse/workers.py

@@ -171,9 +171,6 @@ def load_file_preview(
     repository dict, an archive name, the path of a file in that archive, and a loading indicator
     timer, load the contents of the file and write it into the given file preview widget.
     '''
-    import time
-
-    logger.debug(('before get_archive_file_content', time.time()))
     file_contents = borgmatic.actions.browse.archive.get_archive_file_content(
         config, repository, archive_name, file_path
     )

tests/integration/actions/browse/test_directory_list.py

@@ -122,7 +122,9 @@ def test_add_archive_paths_retains_loading_indicator_at_bottom():
 
 
 def test_directory_list_with_root_directory_adds_loading_indicator():
-    flexmock(module.borgmatic.actions.browse.loading).should_receive('add_inline_loading_indicator').once()
+    flexmock(module.borgmatic.actions.browse.loading).should_receive(
+        'add_inline_loading_indicator'
+    ).once()
 
     directory_list = module.Directory_list(
         config=flexmock(), repository=flexmock(), archive_name='archive'