gistfile1.diff

diff --git a/lib/rack/runtime.rb b/lib/rack/runtime.rb
index 1bd411f..e247d4f 100644
--- a/lib/rack/runtime.rb
+++ b/lib/rack/runtime.rb
@@ -12,10 +12,12 @@ module Rack
       @header_name << "-#{name}" if name
     end
 
+    require 'java'
     def call(env)
-      start_time = Time.now
+      start_time = java.lang.System.nano_time
       status, headers, body = @app.call(env)
-      request_time = Time.now - start_time
+      request_time = java.lang.System.nano_time - start_time
+      request_time /= 1_000_000_000.0
 
       if !headers.has_key?(@header_name)
         headers[@header_name] = "%0.6f" % request_time