Narset's Vanguard against Finale of Revelation results in Loop Prevention System (LPS) agony

BlessedOne

I had Narset, Parter of Veils vanguard in play when my opponent casts Finale of Revelation (FoR).
My opponent happened to be a creatureless Teferi.

At first I thought it was a soft lock; however, the loop prevention system quietly kicked in behind the scenes. 
For the game to continue, I had to wait for the LPS to kick in, then the second phase of the LPS to count down before I could continue.

This was the worst match I had to play in RtO. The match took so damn long because my opponent played many FoR. I think each time this happened it was like 3 minutes. To further add agony to the match, after each instance of this madness, my opponent had an extra swap.

The LPS takes too long to kick in.
What's with the second phase of the LPS?
Why doesn't the LPS stop whatever is going on on the first time it comes up?

Please fix this tinykitty.