I thought about it, but when I compared CX872 to other flights USA bound, the other flights were pretty much on time, i.e. CX870 and CX882, or only with a slight delay. That's why I held off "blaming" the delay as related to the additional security measures.

Then when I looked at the then estimated departure time of CX872 for Dec 27 a few hours before the flight departed, CX.com was already showing the flight as being delayed. CX knew ahead of time that the flight would have been delayed. That led me to believe that was something else causing the delay.

At least on Dec 28 and 29, CX has re-timed the scheduled departure to 7:15pm. So that further confirmed the delay/re-time is operational related.

I do not have much information as to where the equipment came from on the in-bound flight. I only found random information such as one day it was from PVG and the other from LHR.