diff --git a/src/GafferCycles/IECoreCyclesPreview/Renderer.cpp b/src/GafferCycles/IECoreCyclesPreview/Renderer.cpp
index 3d478e984c6..58dac9e3c71 100644
--- a/src/GafferCycles/IECoreCyclesPreview/Renderer.cpp
+++ b/src/GafferCycles/IECoreCyclesPreview/Renderer.cpp
@@ -542,9 +542,8 @@ class ShaderCache : public IECore::RefCounted
 		{
 		}
 
-		void update( ccl::Scene *scene, NodesCreated &shaders )
+		void update( NodesCreated &shaders )
 		{
-			m_scene = scene;
 			updateShaders( shaders );
 		}
 
@@ -1499,9 +1498,8 @@ class InstanceCache : public IECore::RefCounted
 		{
 		}
 
-		void update( ccl::Scene *scene, NodesCreated &object, NodesCreated &geometry )
+		void update( NodesCreated &object, NodesCreated &geometry )
 		{
-			m_scene = scene;
 			updateObjects( object );
 			updateGeometry( geometry );
 		}
@@ -1796,9 +1794,8 @@ class LightCache : public IECore::RefCounted
 		{
 		}
 
-		void update( ccl::Scene *scene, NodesCreated &nodes )
+		void update( NodesCreated &nodes )
 		{
-			m_scene = scene;
 			updateLights( nodes );
 		}
 
@@ -3166,17 +3163,7 @@ class CyclesRenderer final : public IECoreScenePreview::Renderer
 				m_sessionParams.device = firstCPUDevice();
 			}
 
-			if( m_session )
-			{
-				// A trick to retain the same pointer when re-creating a session.
-				m_session->~Session();
-				new ( m_session ) ccl::Session( m_sessionParams, m_sceneParams );
-			}
-			else
-			{
-				m_session = new ccl::Session( m_sessionParams, m_sceneParams );
-			}
-
+			m_session = new ccl::Session( m_sessionParams, m_sceneParams );
 			m_session->progress.set_update_callback( function_bind( &CyclesRenderer::progress, this ) );
 
 			m_scene = m_session->scene;
@@ -3205,9 +3192,9 @@ class CyclesRenderer final : public IECoreScenePreview::Renderer
 			// Add every shader each time, less issues
 			m_shaderCache->nodesCreated( m_shadersCreated );
 
-			m_lightCache->update( m_scene, m_lightsCreated );
-			m_instanceCache->update( m_scene, m_objectsCreated, m_geometryCreated );
-			m_shaderCache->update( m_scene, m_shadersCreated );
+			m_lightCache->update( m_lightsCreated );
+			m_instanceCache->update( m_objectsCreated, m_geometryCreated );
+			m_shaderCache->update( m_shadersCreated );
 		}
 
 		void updateOptions()
@@ -3266,18 +3253,6 @@ class CyclesRenderer final : public IECoreScenePreview::Renderer
 				//film->tag_update( m_scene );
 				integrator->tag_update( m_scene, ccl::Integrator::UPDATE_ALL );
 			}
-
-			// If anything changes in scene or session, we reset.
-			if( m_scene->params.modified( m_sceneParams ) ||
-				m_session->params.modified( m_sessionParams )
-			)
-			{
-				// Flag it true here so that we never mutex unlock a different scene pointer due to the reset
-				if( m_renderState != RENDERSTATE_RENDERING )
-				{
-					reset();
-				}
-			}
 		}
 
 		void updateOutputs()
@@ -3501,49 +3476,6 @@ class CyclesRenderer final : public IECoreScenePreview::Renderer
 			m_outputsChanged = false;
 		}
 
-		void reset()
-		{
-			m_session->cancel();
-			m_renderState = RENDERSTATE_READY;
-			// This is so cycles doesn't delete the objects that Gaffer manages.
-			m_scene->objects.clear();
-			m_scene->geometry.clear();
-			m_shaderCache->flushTextures();
-			m_scene->shaders.resize( m_shaderCache->numDefaultShaders() );
-			m_scene->lights.clear();
-
-			const ccl::Integrator integratorCopy = *m_scene->integrator;
-			const ccl::Background backgroundCopy = *m_scene->background;
-			const ccl::Film filmCopy = *m_scene->film;
-
-			init();
-
-			// Re-apply the settings for these.
-			for( const ccl::SocketType &socketType : m_scene->integrator->type->inputs )
-			{
-				m_scene->integrator->copy_value(socketType, integratorCopy, *integratorCopy.type->find_input( socketType.name ) );
-			}
-			for( const ccl::SocketType &socketType : m_scene->background->type->inputs )
-			{
-				m_scene->background->copy_value(socketType, backgroundCopy, *backgroundCopy.type->find_input( socketType.name ) );
-			}
-			for( const ccl::SocketType &socketType : m_scene->film->type->inputs )
-			{
-				m_scene->film->copy_value(socketType, filmCopy, *filmCopy.type->find_input( socketType.name ) );
-			}
-
-			m_scene->background->set_shader( m_scene->default_background );
-
-			m_scene->shader_manager->tag_update( m_scene, ccl::ShaderManager::UPDATE_ALL );
-			m_scene->integrator->tag_update( m_scene, ccl::Integrator::UPDATE_ALL );
-			m_scene->background->tag_update( m_scene );
-
-			m_session->stats.mem_peak = m_session->stats.mem_used;
-			// Make sure the instance cache points to the right scene.
-			updateSceneObjects( true );
-			m_scene->geometry_manager->tag_update( m_scene, ccl::GeometryManager::UPDATE_ALL );
-		}
-
 		void updateCamera()
 		{
 			// Check that the camera we want to use exists,