Conditional AST timing.

pkg/analyzer/lib/src/task/dart.dart

Index: pkg/analyzer/lib/src/task/dart.dart
diff --git a/pkg/analyzer/lib/src/task/dart.dart b/pkg/analyzer/lib/src/task/dart.dart
index 408db9e179fd4428465287be74c85d0dd8830b46..063a7d9ab2793a40ac1a328dd4c0d97c936345d7 100644
--- a/pkg/analyzer/lib/src/task/dart.dart
+++ b/pkg/analyzer/lib/src/task/dart.dart
@@ -2815,13 +2815,16 @@ class GenerateLintsTask extends SourceBasedAnalysisTask {
     //
     List<AstVisitor> visitors = <AstVisitor>[];
 
+    bool timeVisits = analysisOptions.enableTiming;
     List<Linter> linters = getLints(context);
     for (Linter linter in linters) {
       AstVisitor visitor = linter.getVisitor();
       if (visitor != null) {
         linter.reporter = errorReporter;
-        visitors
-            .add(new TimedAstVisitor(visitor, lintRegistry.getTimer(linter)));
+        if (timeVisits) {
+          visitor = new TimedAstVisitor(visitor, lintRegistry.getTimer(linter));
+        }
+        visitors.add(visitor);
       }
     }