*vc-diff*.diff

diff --git a/magit.el b/magit.el
index 4b3c1fa..4d5a108 100644
--- a/magit.el
+++ b/magit.el
@@ -1075,13 +1075,29 @@ Read `completing-read' documentation for the meaning of the argument."
 (defun magit-cmd-insert (cmd args)
   (insert (magit-cmd-output cmd args)))
 
+(defun magit-perf-log (msg)
+  "Log a msg to the magit perf log"
+  (flet ((message (&rest args) (ignore)))
+    (with-temp-buffer
+      (insert msg)
+      (append-to-file (point-min)
+                      (point-max)
+                      "/tmp/magit-perf-log.txt"))))
+
 (defun magit-cmd-output (cmd args)
-  (with-output-to-string
-    (with-current-buffer standard-output
-      (apply #'process-file
-             cmd
-             nil (list t nil) nil
-             args))))
+  (let ((time-before (float-time)))
+    (magit-perf-log (format "Running %s %s\n" cmd args))
+    (with-output-to-string
+      (with-current-buffer standard-output
+        (apply #'process-file
+               cmd
+               nil (list t nil) nil
+               args)))
+    (magit-perf-log (format "%s %s  --> Elapsed: %f seconds\n"
+                            cmd
+                            args
+                            (- (float-time)
+                               time-before)))))
 
 (defun magit-git-string (&rest args)
   (magit-trim-line (magit-git-output args)))