Speed up execution a bit by removing some walks

src/librustdoc/visit_ast.rs

@@ -451,6 +451,26 @@ fn visit_item(&mut self, i: &'tcx hir::Item<'tcx>) {
     }
 
     fn visit_mod(&mut self, _: &hir::Mod<'tcx>, _: Span, _: hir::HirId) {
-        // handled in `visit_item_inner`
+        // Handled in `visit_item_inner`
+    }
+
+    fn visit_use(&mut self, _: &hir::UsePath<'tcx>, _: hir::HirId) {
+        // Handled in `visit_item_inner`
+    }
+
+    fn visit_path(&mut self, _: &hir::Path<'tcx>, _: hir::HirId) {
+        // Handled in `visit_item_inner`
+    }
+
+    fn visit_label(&mut self, _: &rustc_ast::Label) {
+        // Unneeded.
+    }
+
+    fn visit_infer(&mut self, _: &hir::InferArg) {
+        // Unneeded.
+    }
+
+    fn visit_lifetime(&mut self, _: &hir::Lifetime) {
+        // Unneeded.
     }
 }