Dunno if you still need this, but I came across this the other day while watching the OddLaws streaming server. The hotkey is CTRL+F3 to open the Debug screen + FPS Graph (Bottom of controls page in settings, under Debug and Macros). When you use CTRL+F3, it shows the game version at the top left as well as graphics card being used and the top right shows memory being used which is helpful if a mod has a memory leak.