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    <p>Your benchmark is meaningless (sorry).</p> <p>Making real benchmarks is hard, unfortunately, as compilers are very clever.</p> <p>Things to look for here:</p> <ul> <li>devirtualization: the polymorphic call is expected to be slower because it is supposed to be virtual, but here the compiler can realize than <code>polymorphic_operation</code> is necessarily a <code>OperationAdd</code> and thus directly call <code>OperationAdd::Run</code> without invoking runtime dispatch</li> <li>inlining: since the compiler has access to the methods body, it can inline them, and avoid the function calls altogether.</li> <li>"dead store removal": values that are not used need not be stored, and the computations that lead to them and do not provoke side-effects can be avoided entirely.</li> </ul> <p>Indeed, your entire benchmark code can be optimized to:</p> <pre><code>int main() { boost::timer timer; std::cout &lt;&lt; timer.elapsed() &lt;&lt; " seconds." &lt;&lt; std::endl; timer.restart(); DoOperation* polymorphic_operation = new OperationAdd; std::cout &lt;&lt; timer.elapsed() &lt;&lt; " seconds." &lt;&lt; std::endl; } </code></pre> <p>Which is when you realize that you are not timing what you'd like to...</p> <p>In order to make your benchmark meaningful you need to:</p> <ul> <li>prevent devirtualization</li> <li>force side-effects</li> </ul> <p>To prevent devirtualization, just declare a <code>DoOperation&amp; Get()</code> function, and then in another cpp file: <code>DoOperation&amp; Get() { static OperationAdd O; return O; }</code>.</p> <p>To force side-effects (only necessary if the methods are inlined): return the value and accumulate it, then display it.</p> <hr> <p>In action using this program:</p> <pre><code>// test2.cpp namespace so8746025 { class DoOperation { public: virtual float Run(const float a, const float b) = 0; }; class OperationAdd : public DoOperation { public: float Run(const float a, const float b) { return a + b; } }; class OperationAddOutOfLine: public DoOperation { public: float Run(const float a, const float b); }; float OperationAddOutOfLine::Run(const float a, const float b) { return a + b; } DoOperation&amp; GetInline() { static OperationAdd O; return O; } DoOperation&amp; GetOutOfLine() { static OperationAddOutOfLine O; return O; } } // namespace so8746025 // test.cpp #include &lt;iostream&gt; #include &lt;boost/timer.hpp&gt; namespace so8746025 { // Policy version template &lt; typename operation_policy&gt; struct DoOperationPolicy { float Run(const float a, const float b) { return operation_policy::Operation(a,b); } }; struct OperationPolicy_Add { static float Operation(const float a, const float b) { return a + b; } }; // Polymorphic version class DoOperation { public: virtual float Run(const float a, const float b) = 0; }; class OperationAdd : public DoOperation { public: float Run(const float a, const float b) { return a + b; } }; class OperationAddOutOfLine: public DoOperation { public: float Run(const float a, const float b); }; DoOperation&amp; GetInline(); DoOperation&amp; GetOutOfLine(); } // namespace so8746025 using namespace so8746025; int main() { unsigned int numberOfIterations = 1e8; DoOperationPolicy&lt;OperationPolicy_Add&gt; policy; OperationAdd stackInline; DoOperation&amp; virtualInline = GetInline(); OperationAddOutOfLine stackOutOfLine; DoOperation&amp; virtualOutOfLine = GetOutOfLine(); boost::timer timer; float result = 0; for(unsigned int i = 0; i &lt; numberOfIterations; ++i) { result += policy.Run(1,2); } std::cout &lt;&lt; "Policy: " &lt;&lt; timer.elapsed() &lt;&lt; " seconds (" &lt;&lt; result &lt;&lt; ")" &lt;&lt; std::endl; timer.restart(); result = 0; for(unsigned int i = 0; i &lt; numberOfIterations; ++i) { result += stackInline.Run(1,2); } std::cout &lt;&lt; "Stack Inline: " &lt;&lt; timer.elapsed() &lt;&lt; " seconds (" &lt;&lt; result &lt;&lt; ")" &lt;&lt; std::endl; timer.restart(); result = 0; for(unsigned int i = 0; i &lt; numberOfIterations; ++i) { result += virtualInline.Run(1,2); } std::cout &lt;&lt; "Virtual Inline: " &lt;&lt; timer.elapsed() &lt;&lt; " seconds (" &lt;&lt; result &lt;&lt; ")" &lt;&lt; std::endl; timer.restart(); result = 0; for(unsigned int i = 0; i &lt; numberOfIterations; ++i) { result += stackOutOfLine.Run(1,2); } std::cout &lt;&lt; "Stack Out Of Line: " &lt;&lt; timer.elapsed() &lt;&lt; " seconds (" &lt;&lt; result &lt;&lt; ")" &lt;&lt; std::endl; timer.restart(); result = 0; for(unsigned int i = 0; i &lt; numberOfIterations; ++i) { result += virtualOutOfLine.Run(1,2); } std::cout &lt;&lt; "Virtual Out Of Line: " &lt;&lt; timer.elapsed() &lt;&lt; " seconds (" &lt;&lt; result &lt;&lt; ")" &lt;&lt; std::endl; } </code></pre> <p>We get:</p> <pre><code>$ gcc --version gcc (GCC) 4.3.2 $ ./testR Policy: 0.17 seconds (6.71089e+07) Stack Inline: 0.17 seconds (6.71089e+07) Virtual Inline: 0.52 seconds (6.71089e+07) Stack Out Of Line: 0.6 seconds (6.71089e+07) Virtual Out Of Line: 0.59 seconds (6.71089e+07) </code></pre> <p>Note the subtle difference between devirtualization + inline and the absence of devirtualization.</p>
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    1. COAnd just as a note: be tight about what you time, here you have a memory allocation counting against `OperationAdd` (yes, supposed to be small wrt the loop but still...)
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