Hmm but why is 60hz better then 120hz, how that is connected with game mechanics in a first place?? I bought sim on XBOX/Msoft store but playing on PC.
Is it a bug or what?
Yes, tried for first time running Xbox x at 60hz and now had three flights where there has been no time loss. This change from 120hz seems to have sorted it, and I canāt see any visual degradation as a consequence. Why would change to 60hz solve the clock issue and should I expect to see some visual performance issues as a result?
According to the theory of relativity the measurement of time changes based on the relative motion of the devices measuring it.
Ergo, it is entirely authentic that your aircraftās chronometer would appear to lose time over the course of your flight, compared with the clock that is sitting stationary** on your desk at home. 
** In point of fact, neither you nor your clock are truly stationary, because you are simultaneously spinning around the earthās axis and hurtling across the universe. But Iām simplifying hereā¦
The fact that Asobo had the vision to replicate this time dilation in MSFS is commendable 
- even if some of us on these forums may debate the decision to prioritise it ahead of other features of the sim.
Unless you were flying westward, that is, in which case it sounds like a bug to meā¦
Learn more: HafeleāKeating experiment - Wikipedia
Pmdg 777f time slow too