If the simulator’s measurement of time is incorrect (e.g., the “elapsed time” field has a value less than it should), check your frame rate. If your computer cannot maintain 20 frames per second, simulator time will not match real time; when X-Plane runs slower than 20 fps, it slows down its simulation of real-time so that the simulator is “effectively” running at 20 fps. For instance, if the simulator is running at 10 fps due to extreme rendering settings, X-Plane will run the flight model at half speed. The result is that the physics are integrating in slow-motion in order to avoid destabilizing from the low framerate. Thus, if you need real-time simulation, you must run the simulator at 20 fps or faster.
For instructions on how to appropriately set the rendering options on your specific computer, see “Setting the Rendering Options for Best Performance” in the X-Plane 11 desktop manual.