Consider using a newer version of ImGui

[m516]

Thank you for providing this demo! It was a great resource for building projects with GLFW and ImGui. I'd just like to note that the ImGui version in this repository is old (four years), and ImGui developers improve the library at a fairly rapid pace. The latest version is less demanding on the CPU, but the code to set it up and use it differ slightly from what's required in this version.

An example on how to use this new version of ImGui is available at its official repository: https://github.com/ocornut/imgui/blob/master/examples/example_glfw_opengl3/main.