I haven't seen a patent application for a time machine, so we can rule out the possibility that they're actually slowing down time.
However, I do wonder how they implement this. Do you change timekeeping in the kernel so that a fraction of extra time must pass for each second to be "counted"?
You are exactly correct. The aforementioned thread[0] on Serverfault mentioned timesmearing with `ntpd -x`, as per [1].
It's a fairly well-known technique for avoiding some weird kernel-related bugs on leap seconds.
However, I do wonder how they implement this. Do you change timekeeping in the kernel so that a fraction of extra time must pass for each second to be "counted"?