timing, is pretty bleak for Expressions

.cproject

@@ -902,6 +902,14 @@
 				<useDefaultCommand>true</useDefaultCommand>
 				<runAllBuilders>true</runAllBuilders>
 			</target>
+			<target name="timeCameraExpression.run" path="build/gtsam_unstable/timing" targetID="org.eclipse.cdt.build.MakeTargetBuilder">
+				<buildCommand>make</buildCommand>
+				<buildArguments>-j5</buildArguments>
+				<buildTarget>timeCameraExpression.run</buildTarget>
+				<stopOnError>true</stopOnError>
+				<useDefaultCommand>true</useDefaultCommand>
+				<runAllBuilders>true</runAllBuilders>
+			</target>
 			<target name="testCombinedImuFactor.run" path="build/gtsam/navigation/tests" targetID="org.eclipse.cdt.build.MakeTargetBuilder">
 				<buildCommand>make</buildCommand>
 				<buildArguments>-j5</buildArguments>

gtsam_unstable/timing/timeCameraExpression.cpp

@@ -0,0 +1,95 @@
+/* ----------------------------------------------------------------------------
+
+ * GTSAM Copyright 2010, Georgia Tech Research Corporation, 
+ * Atlanta, Georgia 30332-0415
+ * All Rights Reserved
+ * Authors: Frank Dellaert, et al. (see THANKS for the full author list)
+
+ * See LICENSE for the license information
+
+ * -------------------------------------------------------------------------- */
+
+/**
+ * @file    timeCameraExpression.cpp
+ * @brief   time CalibratedCamera derivatives
+ * @author  Frank Dellaert
+ * @date    October 3, 2014
+ */
+
+#include <gtsam_unstable/slam/expressions.h>
+#include <gtsam_unstable/nonlinear/BADFactor.h>
+#include <gtsam/slam/ProjectionFactor.h>
+#include <gtsam/slam/GeneralSFMFactor.h>
+#include <gtsam/geometry/Pose3.h>
+#include <gtsam/geometry/Cal3_S2.h>
+
+#include <time.h>
+#include <iostream>
+
+using namespace std;
+using namespace gtsam;
+
+static const int n = 100000;
+
+void time(const NonlinearFactor& f, const Values& values) {
+  long timeLog = clock();
+  GaussianFactor::shared_ptr gf;
+  for (int i = 0; i < n; i++)
+    gf = f.linearize(values);
+  long timeLog2 = clock();
+  double seconds = (double) (timeLog2 - timeLog) / CLOCKS_PER_SEC;
+  // cout << ((double) n / seconds) << " calls/second" << endl;
+  cout << ((double) seconds * 1000000 / n) << " musecs/call" << endl;
+}
+
+int main() {
+
+  // Create leaves
+  Pose3_ x(1);
+  Point3_ p(2);
+  Cal3_S2_ K(3);
+
+  // Some parameters needed
+  Point2 z(-17, 30);
+  SharedNoiseModel model = noiseModel::Unit::Create(2);
+
+  // Create values
+  Values values;
+  values.insert(1, Pose3());
+  values.insert(2, Point3(0, 0, 1));
+  values.insert(3, Cal3_S2());
+
+  // UNCALIBRATED
+
+  // Dedicated factor
+  // Oct 3, 2014, Macbook Air
+  // 4.44887 musecs/call
+  GeneralSFMFactor2<Cal3_S2> oldFactor2(z, model, 1, 2, 3);
+  time(oldFactor2, values);
+
+  // BADFactor
+  // Oct 3, 2014, Macbook Air
+  // 20.7554 musecs/call
+  BADFactor<Point2> newFactor2(model, z,
+      uncalibrate(K, project(transform_to(x, p))));
+  time(newFactor2, values);
+
+  // CALIBRATED
+
+  boost::shared_ptr<Cal3_S2> fixedK(new Cal3_S2());
+
+  // Dedicated factor
+  // Oct 3, 2014, Macbook Air
+  // 3.69707 musecs/call
+  GenericProjectionFactor<Pose3, Point3> oldFactor1(z, model, 1, 2, fixedK);
+  time(oldFactor1, values);
+
+  // BADFactor
+  // Oct 3, 2014, Macbook Air
+  // 17.092 musecs/call
+  BADFactor<Point2> newFactor1(model, z,
+      uncalibrate(Cal3_S2_(*fixedK), project(transform_to(x, p))));
+  time(newFactor1, values);
+
+  return 0;
+}