Benchmark app frame time improvements (#1776)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/mbgl/renderer/renderer_impl.cpp

@@ -382,16 +382,22 @@ void Renderer::Impl::render(const RenderTree& renderTree,
 
     // Ends the RenderPass
     parameters.renderPass.reset();
+
+    const auto startRendering = util::MonotonicTimer::now().count();
     parameters.encoder->present(parameters.backend.getDefaultRenderable());
+    const auto renderingTime = util::MonotonicTimer::now().count() - startRendering;
 
     // CommandEncoder destructor submits render commands.
     parameters.encoder.reset();
 
+    const auto encodingTime = renderTree.getElapsedTime() - renderingTime;
+
     observer->onDidFinishRenderingFrame(
         renderTreeParameters.loaded ? RendererObserver::RenderMode::Full : RendererObserver::RenderMode::Partial,
         renderTreeParameters.needsRepaint,
         renderTreeParameters.placementChanged,
-        renderTree.getElapsedTime());
+        encodingTime,
+        renderingTime);
 
     if (!renderTreeParameters.loaded) {
         renderState = RenderState::Partial;