Disclaimer: This is the first time I have ever really looked into using OpenGL

 void
 run(GLFWwindow *window)
 {
 void *resources = setup();
 glfwSetWindowUserPointer(window, resources);
 
 #ifdef MEASURE
 glfwSwapInterval(0);
 #endif
 
 int viewport_width, viewport_height;
 
 // set for proper resizing of window and viewport
 glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
 
 while (!glfwWindowShouldClose(window))
 {
 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
 glfwGetFramebufferSize(window, &viewport_width, &viewport_height);
 glViewport(0, 0, viewport_width, viewport_height);
 
 draw(resources);
 
 glfwSwapBuffers(window);
 glfwPollEvents();
 #ifdef MEASURE
 printfps();
 #endif
 }
 
 cleanup(resources);
 }

 void
 run(GLFWwindow *window)
 {
 void *resources = setup();
 glfwSetWindowUserPointer(window, resources);
 
 #ifdef MEASURE
 glfwSwapInterval(0);
 #endif
 
 int viewport_width, viewport_height;
 
 // set for proper resizing of window and viewport
 glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
 
 while (!glfwWindowShouldClose(window))
 {
 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
 glfwGetFramebufferSize(window, &viewport_width, &viewport_height);
 framebuffer_size_callback(window, viewport_width, viewport_height);
 
 draw(resources);
 
 glfwSwapBuffers(window);
 glfwPollEvents();
 #ifdef MEASURE
 printfps();
 #endif
 }
 
 cleanup(resources);
 }

Bugs

Optimization

• There are two ways to process pending events. glfwPollEvents() processes only those events that have already been received and then returns immediately. This is the best choice when rendering continually, like most games do.

  If instead you only need to update your rendering once you have received new input, glfwWaitEvents() is a better choice. It waits until at least one event has been received, putting the thread to sleep in the meantime, and then processes all received events just like glfwPollEvents() does. This saves a great deal of CPU cycles and is useful for, for example, many kinds of editing tools.

I plan to further expand this answer as I work to optimize this code. This answer is only preliminary right now, and points out what I have found.

Bugs

Optimization

• Running my own profiling tests for a longer duration, I came up with the following data.

enter image description here

As we can see, glDrawElementsInstanced() now only takes up 2% of the total run time. The big time hogs are CGLFlushDrawable and _glfwPlatformPollEvents.

• There are two ways to process pending events. glfwPollEvents() processes only those events that have already been received and then returns immediately. This is the best choice when rendering continually, like most games do.

  If instead you only need to update your rendering once you have received new input, glfwWaitEvents() is a better choice. It waits until at least one event has been received, putting the thread to sleep in the meantime, and then processes all received events just like glfwPollEvents() does. This saves a great deal of CPU cycles and is useful for, for example, many kinds of editing tools.