diff --git a/main.cc b/main.cc
index 681e469..e2dbd3a 100644
--- a/main.cc
+++ b/main.cc
@@ -72,8 +72,10 @@ T_Main::T_Main( )
 
 void T_Main::mainLoop( )
 {
-	T_Profiler::Profiler.clear( );
+	auto& p( T_Profiler::Profiler );
+	p.clear( );
 	while ( !done ) {
+		p.startFrame( );
 		T_Profiler::Profiler.start( "Full frame" );
 		startIteration( );
 		if ( !done ) {
@@ -84,11 +86,13 @@ void T_Main::mainLoop( )
 			T_Profiler::Profiler.end( "Full frame" );
 			SDL_GL_SwapWindow( window );
 
-			auto const& p( T_Profiler::Profiler );
+			p.endFrame( );
 			const auto n( p.sections( ) );
 			for ( auto i = 0u ; i < n ; i ++ ) {
-				printf( "%s: %fms\n" , p.nameOf( i ).c_str( ) ,
-						p.resultOf( i ) );
+				printf( "%s: %fms (start %fms)\n" ,
+						p.nameOf( i ).c_str( ) ,
+						p.durationOf( i ) ,
+						p.startOf( i ) );
 			}
 		}
 	}
@@ -176,10 +180,10 @@ void T_Main::makeUI( )
 
 void T_Main::render( )
 {
-	T_Profiler::Profiler.start( "Effects" );
+	T_Profiler::Profiler.start( "Render" );
 	raymarcher->render( );
 	bloomPass->render( );
-	glFinish( ); T_Profiler::Profiler.end( "Effects" );
+	glFinish( ); T_Profiler::Profiler.end( "Render" );
 
 	glUseProgram( 0 );
 	ImGui::Render( );
diff --git a/profiling.cc b/profiling.cc
index e42df8a..b52d999 100644
--- a/profiling.cc
+++ b/profiling.cc
@@ -8,6 +8,10 @@
 
 T_Profiler T_Profiler::Profiler;
 
+constexpr uint32_t T_Profiler::Samples;
+constexpr uint32_t T_Profiler::History;
+constexpr uint32_t T_Profiler::Invalid;
+
 
 void T_Profiler::clear( )
 {
@@ -18,6 +22,32 @@ void T_Profiler::clear( )
 
 void T_Profiler::startFrame( )
 {
+	previous_ = Invalid;
+	current_ = Invalid;
+}
+
+void T_Profiler::endFrame( )
+{
+	const auto n( sections_.size( ) );
+	while ( secDurations_.size( ) < n ) {
+		secDurations_.push_back( 0 );
+		secStarts_.push_back( 0 );
+	}
+
+	for ( auto i = 0u ; i < n ; i ++ ) {
+		const float d = computeDuration( i );
+		secDurations_[ i ] = d;
+		if ( parents_[ i ] != Invalid ) {
+			assert( parents_[ i ] < i );
+			secStarts_[ i ] = secStarts_[ parents_[ i ] ];
+		} else if ( chain_[ i ] != Invalid ) {
+			assert( chain_[ i ] < i );
+			secStarts_[ i ] = secStarts_[ chain_[ i ] ]
+				+ secDurations_[ chain_[ i ] ];
+		} else {
+			secStarts_[ i ] = 0;
+		}
+	}
 }
 
 void T_Profiler::start(
@@ -29,8 +59,19 @@ void T_Profiler::start(
 		sections_.push_back( section );
 		samples_.push_back( T_SamplesList_{ } );
 		starts_.push_back( 0u );
+		chain_.push_back( Invalid );
+		parents_.push_back( Invalid );
 	}
 
+	chain_[ pos ] = previous_;
+	if ( current_ != Invalid ) {
+		parents_[ pos ] = current_;
+		previous_ = Invalid;
+	} else {
+		parents_[ pos ] = Invalid;
+	}
+	current_ = pos;
+
 	struct timespec ts;
 	clock_gettime( CLOCK_MONOTONIC , &ts );
 	starts_[ pos ] = ts.tv_sec * 1000000000 + ts.tv_nsec;
@@ -63,9 +104,12 @@ void T_Profiler::end(
 	}
 	samples[ 0 ].sum += float( duration ) * 1e-6;
 	samples[ 0 ].nSamples ++;
+
+	previous_ = pos;
+	current_ = Invalid;
 }
 
-float T_Profiler::resultOf(
+float T_Profiler::computeDuration(
 		__rd__ const uint32_t section ) const
 {
 	auto const& samples( samples_[ section ] );
diff --git a/profiling.hh b/profiling.hh
index 313e3db..b4c7e7c 100644
--- a/profiling.hh
+++ b/profiling.hh
@@ -18,6 +18,7 @@ struct T_Profiler
 {
 	static constexpr uint32_t Samples = 4;
 	static constexpr uint32_t History = 4;
+	static constexpr uint32_t Invalid = 0xffffffff;
 	static T_Profiler Profiler;
 
 	void clear( );
@@ -25,6 +26,7 @@ struct T_Profiler
 	void startFrame( );
 	void start( __rd__ std::string const& section );
 	void end( __rd__ std::string const& section );
+	void endFrame( );
 
 	uint32_t sections( ) const noexcept
 		{ return sections_.size( ); }
@@ -33,15 +35,29 @@ struct T_Profiler
 			__rd__ const uint32_t section ) const
 		{ return sections_[ section ]; }
 
-	float resultOf( __rd__ const uint32_t section ) const;
+	float durationOf( __rd__ const uint32_t section ) const
+		{ return secDurations_[ section ]; }
+	float startOf( __rd__ const uint32_t section ) const
+		{ return secStarts_[ section ]; }
 
     private:
 	using T_SamplesList_ = std::vector< T_ProfilerSamples >;
 	using T_Data_ = std::vector< T_SamplesList_ >;
 
 	uint32_t find( __rd__ std::string const& section ) const;
+	float computeDuration(
+			__rd__ const uint32_t section ) const;
+
+	uint32_t previous_;
+	uint32_t current_;
 
 	std::vector< std::string > sections_;
+	std::vector< uint32_t > chain_;
+	std::vector< uint32_t > parents_;
 	T_Data_ samples_;
 	std::vector< uint64_t > starts_;
+
+	std::vector< float > secDurations_;
+	std::vector< float > secStarts_;
 };
+