diff --git a/README.md b/README.md
index 30402b6..083fcdc 100644
--- a/README.md
+++ b/README.md
@@ -75,6 +75,12 @@ This adds the caller as 'method' like so:
 time="2015-03-26T01:27:38-04:00" level=fatal method=arcticcreatures.migrate msg="a penguin swims by" animal=penguin
 
 ```
+Note that this does add measurable overhead - the cost will depend on the of Go, but is between 20 and 40% in recent tests with 1.6 and 1.7.  You can validate this in your environment via benchmarks:
+```
+go test -bench=.*CallerTracing
+```
+
+
 #### Example
 
 The simplest way to use Logrus is simply the package-level exported logger: