Hello everyone.
If you have two screens, there is also HWiNFO (
https://www.hwinfo.com/ ) which is free for personal use and can also give information on many other parameters such as memory usage, processor usage, ...
It also has the advantage of presenting historical data, not just current data.
He also shows the difference between what is presented, by the game, to the graphics system "FPS Presented" and what is displayed by the screen "FPS displayed". For example, on my laptop with two additional screens connected, I can see that for the same sequence, the "FPS Displayed" is much higher when the TrainZ window is displayed on the laptop screen than when it's displayed on one of the two additional screens. These are good screens, but not gaming screens. The adaptateu also plays a role.
As I understand it, TrainZ's statistics show "FPS Presented", which isn't necessarily what you see on screen. As always, it's the slowest link in the chain that determines performance.