avoid startswith since can be expensive on some machines

jdaviz/app.py

@@ -603,7 +603,7 @@ def _on_layers_changed(self, msg):
                 self.state.layer_icons = {
                     **self.state.layer_icons,
                     layer_name: alpha_index(len([ln for ln, ic in self.state.layer_icons.items()
-                                                 if not ic.startswith('mdi-') and
+                                                 if not ic[:4] == 'mdi-' and
                                                  self._get_assoc_data_parent(ln) is None]))
                 }