# Drastic performance decrease when full screen vs almost full screen

**URL:** <https://discourse.glfw.org/t/drastic-performance-decrease-when-full-screen-vs-almost-full-screen/2631>\
**Category:** support\
**Created:** [May 14, 2024, 2:30am UTC](https://discourse.glfw.org/t/drastic-performance-decrease-when-full-screen-vs-almost-full-screen/2631 "2024-05-14T02:30:05Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![dougbinks](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.glfw.org/dougbinks/32/39_2.png) [@dougbinks](https://discourse.glfw.org/u/dougbinks)\
**Post date:** [May 16, 2024, 8:03pm UTC](https://discourse.glfw.org/t/drastic-performance-decrease-when-full-screen-vs-almost-full-screen/2631/5 "2024-05-16T20:03:44Z")

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I am a bit a bit puzzled, but I don’t know what to expect from this system + setup. Do you have any other fullscreen OpenGL non-GLFW apps you can test with?

It might also be worth checking that you’re setting the same mode (bits as well as refresh rate):

```auto
const GLFWvidmode* mode = glfwGetVideoMode(monitor);
 
glfwWindowHint(GLFW_RED_BITS, mode->redBits);
glfwWindowHint(GLFW_GREEN_BITS, mode->greenBits);
glfwWindowHint(GLFW_BLUE_BITS, mode->blueBits);
glfwWindowHint(GLFW_REFRESH_RATE, mode->refreshRate);
 
GLFWwindow* window = glfwCreateWindow(mode->width, mode->height, "My Title", monitor, NULL);

```

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