Time isn't slowing down, but the Earth's rotation is. Consequently, noon is a little later each day, and every now and then, authorities have to add a leap-second to make it when the Sun is overhead in London.
Some American scientists are agitating for this to stop being added, possibly because it makes then have to adjust their atomic clocks. If they get their way, in umpteen million years, noon will be in the middle of the night.
Greenwich Meridian rules OK, so far
That was on the news just one hour ago.

Azizi, the only time time slowed down for me, I came down the next day.....