I have just started using the new Nvidia App overlay and there is a useful HUD display in it with fps, GPU usage, CPU usage and latency which is great and super easy for evaluating your system but the screen shot pics do not have it. Very configurable so you can place it on the screen as not to interfere with any other text by just pressing ALT-Z.
Not sure if its possible to change that in Zwift, possibly not but it makes a useful reference if you want to show others what your setup is capable of. No big deal but it could be a quick fix for Zwift.